This guy say you don't need to join a hacker collective before federal agents can follow your trail in cyber space.

Matthew Olsen is the head lawyer at the NSA. He's also been nominated to run the National Counter Terrorism Center, and yesterday he told a Senate committee that in certain circumstance agents can use cell phone data to track the movements of Americans as the travel around the country.
The idea that the NSA can do this surprises no one. That the agencies top lawyer would say publically that agents are legally allowed to do it - well that's worth noting.
Tracking cell phone users isn't simple but it's becoming more and more common. Last year two hackers working for a Colorado garage were able to pull it off. And Polaris, a silicon valley start-up, makes of business of selling this technology to Middle eastern potentates. Crafting a legal rational to use it on Americans inside the US maybe the trickiest hurdle left. Oslen told that Senate that was "a very complicated question," and his staff is now working on a memo to provide a fuller picture.