The US Army has officially blocked Twitter on its networks:

The Army announced the other day that it would get a million or more followers on micro-messaging site Twitter, just like “Punk’d” host and social networking superstar Ashton Kutcher. But catching to Mr. Demi won’t be easy — since many Army bases block Twitter on its networks.

“The Army has reached new levels of incoherent in its information security policy as its Public Affairs Office begins a Twitter based campaign while its Information Technology office blocks Twitter from Army computers,” one frustrated Army civilian employee tells Danger Room. “This continues a pattern of bizarre behavior such as promoting blogs while blocking them, and blocking access from Army computer networks to the American Enterprise Institute, the Stanley Foundation, Russian government sites, bin Laden’s fatwahs, and firearm manufacturers.”  [Danger Room]

I can actually understand this, would the Army want Soldiers Twittering all day at work?  I think this more of a work productivity thing then any real censorship.