What no Twitter?

Looks like the Marine Corps is shutting down access to social networking sites like Twitter, Facebook and MySpace, using government computers on government networks. Use on personal computers will be OK. Is the Army far behind with such a move? I see the point from a Department of Defense standpoint, but then I look at some of the very senior officers in all services who have their own Twitter page, etc. Whatever happens, it will be interesting to watch from the sidelines. As for me, I definitely do not Twitter, nor do I ever plan to be a Twitterer, whatever that is.