I disagree. When it comes to this technology, the private sector is on the cutting edge of this stuff. We're still in the terabyte world, and it drives us nuts. Think data feeds from 25 million companies, because, under the Patriot Act, ALL businesses are required to report any transaction over $10,000. I don't think the feds have thought through the problem of maintaining that kind of data - and it won't even have a linking key like IRS data.
This is the kind of crap I deal with for a living - and the more I think about this, the more I believe this DARPA matter is more comical than sinister, except for the fact that such a database would be potentially useful for lookups instead of modelling.