'You are now one out of 100,409 eligible beta candidates.
Good Luck!"
I plugged in a PS3 controller. I downloaded MotioninJoy, because I didn't want to spend time installing anything else and I was trying to finish within the first hundred thousand. I first tried Braid, and although I could bring up the Steam cloud, I couldn't do anything else in the game with the controller. I selected Left 4 Dead 2 and launched it with the controller, and found that once I was in the game I had to go into options and specifically enable gamepads. I did that and it was pretty fun, but I must have calibrated the gamepad wrong because I couldn't turn to the left or right (just move and aim up and down) and moving also triggered the "shoot" button. Oh, before I enabled the gamepad, I did have to hit the left mousebutton to select the person that I was playing -- nothing on the gamepad would let in to get into the options until I hit the mouse button. After that I exited the game and I had the "achievement" which let me get into the beta. I hope I win, although with only 300 machines and more than a hundred thousand people, that's pretty unlikely.

I think there's probably a chance that with a larger active friend list I'll have a better chance to get in, but I don't want popups all the time about who's now playing which game. If anyone else responds to this post, I'll friend you.