Hey, Vivek talks about this way better than I have in a posting on TechCrunch, so I'll just stop talking and quote him:
Eighteen months ago, data.gov was born, with the release of 47 government data sets of information. Today, there are more than 250,000 data sets and hundreds of applications that use them. New data sets are being made available every week, and localities like San Francisco, New York City, the State of California, and the Commonwealth of Massachusetts have launched web sites. Countries such as Canada, Australia, and the U.K are also releasing their data. Tim Berners-Lee, inventor of the world worldwide web, is behind the U.K. effort. And legendary publisher Tim O’Reilly is championing a new movement, called Gov 2.0, to maintain the momentum of change.
What is happening with the opening up of government data is nothing less than a silent revolution. There are literally thousands of new opportunities to improve government and to improve society—and to make a fortune while doing it. Unlike the Web 2.0 space, which is overcrowded, Gov 2.0 is uncharted territory: a new frontier to explore, grow things on, and settle on. It’s fresh soil for unlikely seedling ideas that, if they take root, could lead to very successful ventures. So I encourage entrepreneurs to stake their claims as soon as they can.