data.gov may be the most important idea so far, but it will only work if the government also takes explicit steps to (a) get as much data as possible onto the site; and (b) takes aggressive steps to make the public aware of the site and what is on it. I suggest some or all of the following:
1. prizes for the best app based on data from data.gov
2. prizes for the best use of data from data.gov
3. require/encourage/whatever all press releases about new data to mention that such new data is/are available on data.gov
4. mention time and again in speeches from Obama, Biden, cabinet secretaries, Senators and Reps, et al.