Corporate firewall man. It feels wrong, but in my group, we have to block everything. Facebook, Twitter, literally every site having to do with games of any sort, yahoo, hotmail, gmail, this very site... and on and on.
Just a little word of warning form anyone that would not know how these things work, but the filters send every new site accessed directly to the inbox of the IT admins. There it is reviewed and blocked due to content. Games, Pornography, Media Sharing, Illegal/illicit and Gore are the primary categories that every company seems to block.. If anything can be construed as any of those things, its blocked permanently. If you access a site successfully one day, and get blocked the next it is your own doing. Big brother knows what you were doing, and where you sat. Any large spike in bandwith like using a port to play a game won't last long.
It works that way in the past four networks I have administered, though none of them were schools. Schools usually don't have as rigid of a filter, and/or not as many eyeballs on traffic, but they still have enough to limit gaming on their networks though. If you find yourself on filtered networks often, look into getting a WISP, such a Clearwire. They have enough speed to play NWN (At least one player I know uses it exclusively, to play PotM) and the prices and coverage are soooo much better than they once were.
