So they know who the people are who visit and post on these sites?
The US had stealth technology for ten years before they let the public in on it. Our military is now perfecting laser weapons that can vaporize a moving target out of the sky. The government's prowess in information processing is even further advanced (although their own internal security sucks beyond belief).
Ever heard of Echelon? Look it up sometime. You have no real anonymity on the internet.