TF2 Beta, again Valve is going to expand its testing base to everyone that owns TF2.
http://www.teamfortress.com "The beta is available to anyone that owns a copy of TF2. To install, launch Steam, open the Library and install "Team Fortress 2 Beta" from your games list." I know what you're thinking...
Q: It shipped already why do I want to play the Beta!? A: Because they're making some changes and they need your help to test, besides they're adding some new stuff and you need to check it out! For the purpose of testing they also give you the achievement based unlockables. These do not carry over to the actual game but if you've wondered what it would be like to do X with Y weapon, now is your chance.
So there ya go, get your butt in game and check out the good stuff, you might see some things from your fellow polycounters.