Air Force Blocks Access to Many Blogs
blog.wired.com
blog.wired.com
It doesn't restrict personnel/private Internet, ie. when you go to a comm center to pay for the Internet or if you install cable into your barrack room. It's not so much censorship as increasing productivity like all major corporations.
Maybe RescueTime should pitch to the Pentagon.
Even in ordinary companies I doubt whether restricting internet access leads to improved productivity. A worker intent on wasting time will find a new way of doing it if you restrict his internet.