The competition to be the best stop for single sign-on technology and an enabler of data portability took another interesting turn today with the launch of Yahoo! Updates, a service that lets people log into participating Web sites with their Yahoo accounts and stream content back to key channels across Yahoo properties, such as Yahoo Mail or My Yahoo (personalized web pages). At some point, many websites will be faced with a choice. For your users' convenience at sign-on time, do you use Facebook's increasingly popular Facebook Connect technology? Or Google's Friend Connect? Or now Yahoo! Updates? Or do you put a button for all of them in the log-in and comment sections of your site? It probably depends on the website, because each of these data portability initiatives do different things well. Unfortunately for Yahoo, this product could knock it out of the park from a technology perspective and people might not give it a chance due to the company's ongoing financial and strategic woes. The technology does sound solid, though. Consider the opinion of Marshall Kirkpatrick of ReadWriteWeb, who shared his take on Yahoo Updates this morning. The "user experience is immediately quite usable and full-featured," he wrote "The same type of pop-up window asks users to grant permission to JS-Kit (or any other site using Yahoo! Updates) to access their Yahoo! profile information." So add Yahoo Updates to the list of options along with Facebook Connect and Google Friend Connect. Facebook enjoys some key advantages over its two rivals. For one, the trove of data contained in a Facebook profile mirrors what a lot of third-party sites look for from users who sign into their sites. Interests, movies, activities, and birth date are perfect examples. It's the type of highly personal information that many people share on Facebook, and don't mind sharing with other sites provided their privacy settings extend throughout \u2014 a goal that Facebook platform guys like Dave Morin have told me they are highly focused on achieving. Google's Friend Connect takes a slightly different approach than Facebook Connect, by saying you should have a variety of sources to use when moving your identity around the Web, including your Gmail or Yahoo e-mail address, or a Twitter profile, for example. Google makes a compelling argument. If all of all of your friends aren't on Facebook, why rely on that as the sole way to carry your identity? But although Google's Friend Connect is a great single sign-on tool for individual websites and will help traffic growth at those sites, it suffers a fundamental problem: no Facebook. (Facebook banned its API from Friend Connect) Google doesn't have a social networking site as powerful as Facebook to stream information back to from third party sites, and if Facebook keeps growing to become the predominant social network, that's a problem. I see an example of this in my everyday life. I use Facebook Connect to log into MapMyRun. Actions I take on the site will be published to my Facebook feed at my discretion. Since I like sharing my running routes with friends on Facebook, many of whom share the hobby with me, I use this option. If I logged in with Yahoo! Updates or Friend Connect to MapMyRun (not that is an option, but for the sake of argument), I'm not sure where I'd publish that information. Perhaps my (very non-social) iGoogle page or my Orkut account (ha, right). Facebook has taken a Microsoft-ian approach, saying it's our way or the highway when it comes to single sign-on technology \u2014 much as Redmond did with its failed Passport program earlier this decade. But Facebook is unlikely to suffer the same fate because its presence on the Web is far more sophisticated and its technology far better designed than Microsoft's internet products. There's also the 175 million Facebook users to consider, who I don't believe are as fickle and ready to jump ship as people think. That loyalty will be cemented even more everyday as their pictures, videos and comments live in the Facebook environment, and it becomes harder to leave. Yes, as Mark Zuckerberg wrote in February, Facebook users own their data. Yet I somehow doubt scraping all your content off Facebook and taking it somewhere else would be an easy affair. Ideally, all of these companies should play nicely and come up with one solution to the problem that lets users choose what distribution channels to publish their content across. Unfortunately, history dictates we should expect otherwise, and an ensuing single sign-on war could leave the Web as fragmented as ever.