One of the neatest tricks in all the Harry Potter novels is the Marauder\u2019s Map. Armed with this magical tell-all, wizard-in-training Harry could see the whereabouts of anyone inside the Hogwarts school. And thanks to some clever technology, visitors to several Smithsonian museums can take advantage of their own magical map.Through the use of wireless handheld devices, visitors to the Smithsonian Information Center at the Castle, the National Museum of American History, the National Postal Museum, and the National Air and Space Museum\u2019s Udvar-Hazy Center can track their progress through the exhibits. (A fifth museum, the National Museum of Natural History, is slated to adopt the technology in mid- to late July.) Rent one of the handhelds, and you get not only a map but also an interactive list of exhibits, guided tours to follow, even instant messaging and location tracking for other members of your group\u2014a great feature when it\u2019s time to round up the kids.The Smithsonian isn\u2019t alone; other museums are busily implementing a variety of forms of ubiquitous (a.k.a. pervasive) computing to assist customers. Some would argue that their efforts are not truly pervasive\u2014the zenith of which would be environments that simply react to people without direct input or cumbersome interfaces. However, what the museums learn about things such as delivering personalized multimedia content to mobile users, luring visitors to lesser-known exhibits and identifying how people react to interactive surroundings will help create applications for retail, entertainment and other industries. Big SISmithsonian\u2019s map is but one part of the SIguide (pronounced "sigh guide") initiative, an ambitious two-year pilot project slated to launch by the end of the summer that will study handhelds\u2019 effectiveness in the museums. My Le Ducharme, SIguide\u2019s project leader, says she hopes the project will produce a better museum experience for visitors, allowing them to "spend more time here and learn more." She notes, for instance, that the average visitor spends only a few minutes in the huge gems and minerals hall. She hopes that an interactive guide might prompt visitors to spend more time in this and other underutilized exhibits.SIguide represents a significant project in pervasive computing. With its 1,000 handhelds in place, it is "by many orders of magnitude the largest project of its type in the world," according to Ted Paschkis, CEO of Wivid Systems, which developed the Smithsonian\u2019s system. In addition to the maps, the handhelds will link visitors to hundreds of video clips and pictures; in due time, they will also invite users to go on scavenger hunts for objects throughout the museums. Museumgoers can even use the handhelds to view interactive video clips of items that people can\u2019t actually see, such as the inside of Thomas Jefferson\u2019s desk. (Retailers and others could imagine similar technology as a sales tool, perhaps showing customers a video of a product in action on their PDA or cell phone.)The handhelds will also enable museumgoers to build centrally stored scrapbooks of their visits. Leave one museum to go to another, and you\u2019ll leave the handheld behind. But you\u2019ll bring your session identity with you, which you can use in the next museum, or even on your next trip to Washington, D.C. The handhelds also use location-tracking technology to make sure that content related to nearby exhibits is available. Interested in a particular work or artist? The map will show you where to find other displays you might like. New Uses for Olde TechThe technology behind these projects isn\u2019t particularly advanced. Off-the-shelf (with some minor tweaking) wireless Hewlett-Packard iPaq HX4700 handhelds connect to standard back-end servers using the now-pedestrian 802.11b standard, and a good amount of the content is pulled from existent multimedia exhibits that the Smithsonian has developed over the years. The scrapbooking feature is simply website bookmarking in a different context. The commonplace nature of the bulk of the technology is helping other museums get in on the activity as well. Projects are in the works at places such as New York\u2019s Museum of Modern Art, Chicago\u2019s Field Museum of Natural History, the University of British Columbia\u2019s Museum of Anthropology, the Cleveland Museum of Art and many others. "That familiar, already-paid-for infrastructure is starting to show up in a lot of places," says Alex (Sandy) Pentland, a professor at MIT who has conducted pioneering research in fields such as wearable computing and pervasive systems. With the infrastructure mostly in place, "customer resistance, capital costs and reliability have all been taken care of. The age of pervasive computing has finally arrived," he says.What Makes It Pervasive?Of course, not all of the museum projects are pervasive, according to the strict definition. In fact, "a lot of what we see at this point, like the installation at the MoMA in New York, if you explained it to some of the luminaries of pervasive computing, they would scoff at it," says Alex Ledin, a senior consultant at SRI Consulting Business Intelligence. He says they would probably call it merely wireless data access, since the technology doesn\u2019t yet respond to users without their direct input. Still, Ledin agrees that what museums are now doing shows that the wireless networking infrastructure needed for pervasive computing is coming together (although wireless networks continue to have dead spots, issues with interference and other as-yet-unresolved flakiness), and that the hardware is ready to go. The weakest point is the lack of well-integrated software that is smart enough to interact with people in a wide variety of places. Even so, Ledin says that the current spate of projects is significant. "They presage a time when you will be able to get information about something around you using a wireless device," he says.They also presage some very interesting potential for how environments will interact with people. Not in the sense of the movie Minority Report, in which Orwellian television monitors use iris-scanning technology to force-feed specially targeted ads and information to Tom Cruise\u2019s on-the-run lead character. Privacy advocates can be thankful that this kind of pervasive technology remains safely in the realm of science fiction. But experiments are already under way to study how museums\u2019 environments can influence what people do in them. The Smithsonian\u2019s interactive maps are just one example. Another comes from Cornell University\u2019s Johnson Museum. In one of the museum\u2019s galleries, sensors monitor for the presence or absence of motion. When they detect minimal activity in a certain section of the gallery, the sensors set off bird noises, which sometimes draw visitors to that section. Kirsten Boehner, a Cornell PhD candidate working on human-computer interaction issues, points to this as a way to help curators create richer museum experiences for visitors. It\u2019s easy to imagine a subliminal "blue light special" at a retailer using similar technology to draw shoppers through a store.Pervasive ProblemsMaintaining pervasive environments presents a particular challenge for museums. Technology changes rapidly, and the handheld platforms in particular present issues: Museums can\u2019t afford to build content that will run on every type of handheld. The cheapest, most widespread versions, cellular phones, aren\u2019t yet very good for displaying video or accessing the Web, because many don\u2019t have color screens or are underpowered for multimedia content delivery.But when sufficiently powerful technology does reach ubiquity, many museums will be ready with the content.For now, Peter S. Samis, the San Francisco Museum of Modern Art\u2019s associate curator of education and program manager of interactive educational technologies, jokes that despite installing a wireless network, the museum\u2019s technology is anything but pervasive. But Samis says he\u2019s focused on building up the museum\u2019s multimedia content (currently available primarily through its visitor education center), attending conferences such as "Museums and the Web" and watching how handheld-based projects unfold at other museums. He expects that the hardware platforms will stabilize in a couple of years, and wireless networks will be much more reliable. When that happens, he\u2019ll be ready to go with his well-developed content library.Management and cost issues, not to mention the potential for damage and theft, aren\u2019t the only concerns museums have with handhelds. One of the biggest issues is that people tend to spend more time looking at the screen than at the exhibits. To combat this problem, technology designers are trying new techniques. Ubiquity Interactive, the company that built the systems in use at the UBC\u2019s Museum of Anthropology, developed what it calls "co-navigation" techniques, in which the screen prompts users to look at aspects of the art. For instance, one of its most famous pieces is the late Bill Reid\u2019s wood sculpture "Raven and the First Men." Ubiquity swathed the 7-foot-tall sculpture with infrared light, so as visitors walk around it, the picture of the sculpture onscreen turns so that they\u2019ll see the same view onscreen as in the room, with accompanying comments from a curator. "There\u2019s this back-and-forth thing between the screen and the actual artifact," says Lars Meyer, one of Ubiquity\u2019s principals.How museums handle these issues may prove telling for commercial ventures that are looking to adopt pervasive computing. "Museums can benefit from a greater range of technology than almost any other industry," says Leonard Steinbach, CIO at the Cleveland Museum of Art. His technology needs range from digital imaging to X-ray technology to infrared, and he\u2019s working on a project that will deploy RFID (see "Putting the RFID in Art"). "Our need for this technology is as complex as a sophisticated marketer\u2019s; we\u2019re creating a communion between art and the viewer on the viewer\u2019s terms. That\u2019s a really daunting supposition."Wivid\u2019s Paschkis thinks there are huge opportunities still to come in pervasive technology. He envisions using nanogyroscopes to get much more precise location information than is currently possible. That will enable museumgoers to, say, take their handheld and pass it over a sarcophagus to view a streamed X-ray image of what\u2019s inside.But that\u2019s tomorrow\u2019s pervasive magic.