Link! I know most of us already have TF2 (duh...), but in case you know someone who doesn't and wants it, or in case you wanna gift it to someone. It's 2.50$. For 40 minutes. Go! Edit: 10 minutes now.
I fear a lot of noobs in the coming weeks. But also it could lead to loads of cheaters. No need to risk being VAC banned on your account with all those games now, when you can make a new one and spend a couple of £/$'s on it over and over. It could be a sad few weeks.