(FORTUNE Magazine) – Robert Shaw is no stranger to coast-to-coast travel. The former Oracle executive and CEO of security software startup ArcSight has lived in the Bay Area for 25 years and road-tripped to New York countless times. But now he's more likely to head to Washington, D.C. "It used to be that you'd stop in and check the heartbeat every once in a while," he says. "Now we have to be there all the time to build relationships." Shaw estimates the number of businesspeople going from Silicon Valley to the D.C. area has increased by at least 200% over the past year. According to the Bureau of Transportation Statistics, there were no nonstop flights from Oakland to Dulles before Sept. 11. Now there are 123 each month.

Tech communities in Silicon Valley, Boston, Seattle, and Austin may be libertarian havens, but these days the geeks are cozying up to big government. Washington, in its rush to bulk up systems for combating terrorism, has set aside $59 billion this year to spend on IT, most of which will go to the Departments of Defense and Homeland Security. That's an 18% boost over last year, and analysts say spending is likely to grow 10% annually for the next few years.

With corporate spending stalled, struggling tech startups are going through contortions--even changing their entire business models--to get a piece of that action. Some industry watchers think government spending is ultimately what will bring the tech sectors, especially in the aforementioned cities, out of their long slumps. "I don't want to say it's like a WPA project, but it's going to help," predicts Zoe Baird, president of the Markle Foundation, which promotes the use of technology in the public good.

Typically large firms such as Unisys, SAIC, and Boeing win the big government contracts. They in turn subcontract to more-specialized companies, like Oracle, Cisco, and L-3 Communications, as well as smaller tech startups. Rick Stephens, head of Boeing's Homeland Security & Services unit, says he gets at least 30 cold calls per week from small to medium-sized enterprises that want to do business.

Cyveillance, a northern-Virginia startup that specializes in Internet espionage software, primarily sells to FORTUNE 500 companies. But recently it signed a government contract with a large systems integrator. So did Groove Networks, a data-sharing company founded by Lotus Notes creator Ray Ozzie: Groove now counts John Poindexter's Total Information Awareness program as a big customer. Mobile-phone operator Nextel estimates that 10% of its customers are now in the public sector, and CEO Tim Donahue predicts the number will grow by at least 20% this year.

But there can be drawbacks to selling to Uncle Sam. In March, Silicon Valley bigwig Mitch Kapor resigned from the board of Groove, in part because he wasn't comfortable with the Big Brother aspects of what the company was doing. He thinks that if tech executives had known they would be in this position today, many might not have gone down the dot-com road in the first place. Now they don't have a choice. "Companies tell themselves, 'We don't have the luxury of thinking about the broader implications. We're in a mode of survival.'" In this economy, beggars can't afford to be choosers. --Christine Y. Chen