Comcast customers in five U.S. cities will have access to 1 Gigabit per second (Gbps) broadband service by the end of the year, the cable giant said this week.\n\n\nHowever,\u00a0Comcast's official announcement left some key questions unanswered. The company didn't say, for example, how much the service or the special modems needed to use it will cost, and whether monthly data caps, an existing and unwelcome feature of Comcast service in some cities, will apply.\n\n\nDespite the remaining questions, the announcement should prove to be good news, because it means Comcast will use a new technology to deliver very fast broadband to its customers without the considerable expense and construction challenges associated with fiber broadband installations. It's also a sign that competition in the broadband market is finally heating up, a shift that will eventually give at least some of the millions of Americans stuck in the Internet slow lane\u00a0access to speedier service.\n\nComcast, gigabit Internet, DOCSIS and you\n\nKnown by the awkward acronym DOCSIS, the new service offers speeds of up to 1Gbps downstream over the cable that already delivers television signals to many homes. (Comcast didn't specify a maximum upload speed.) Customers in Atlanta and Nashville will be able to subscribe early this year, and parts of Chicago, Detroit and Miami will get the service during the second half of the year, according to the company.\u00a0Comcast will "eventually make these ultra-fast speeds available to most homes in our service areas," according to a press release, but no specific timeline for the rollout is available.\u00a0\n\n\nI used the words "parts of" deliberately, because when Comcast and other providers, including Google, announce new services in cities, they often only make them available to customers in a relatively small number of neighborhoods.\n\n\nComcast did not release pricing details, but a spokesman for the company gave me a hint via email about the upper limit. "What we can say is that because a gigabit Internet service using DOCSIS 3.1 will run over our existing infrastructure we expect it to be less expensive than our fiber\u2013based Gigabit for Pro service, which is a symmetrical 2Gbps service that retails at $299.95."\n\n\nThat's double the amount of data than the 1Gpbs service, so will the new offering cost half as much? We'll have to wait and see.\n\n\nComcast also didn't say anything about the cost of modems, but a quick Web search shows DOCSIS 3.0 modems that range from about $70 to $150. Comcast's service utilizes the newer DOCSIS 3.1, so modems compatible with that standard might be more expensive.\n\nGigabit Internet and data caps\n\nAs for data caps, the company spokesman told me Comcast Business customers don't currently have data caps, and that won\u2019t change. He didn't provide any details on consumer data caps. However, it's worth noting that the company is already experimenting with monthly data limits in Atlanta, Miami and Nashville, but not in Chicago or Detroit.\n\n\nComcast and other providers clearly see broadband data caps, similar to the wireless service caps that are common today, as a wave of the future. But these caps could be a real problem for gigabit Internet subscribers. At those speeds, it would be easy to blow through the 300GB cap that's already in place for some customers, and that would obviously make the service less useful and more expensive.\n\n\nAgain, caveats aside, this is good news. Americans have waited a long time for Internet speeds comparable to the service enjoyed by consumers in many parts of Europe and Asia. Progress has been slow going in the United States, but the industry is finally moving in the right direction.