The Steam Forum was hacked according to http://www.1up.com/news/steam-forums-down-after-hack . But, I was never a member of the forum of Steam, or used Steam in the past.
I've never herd of EA level trolling but a number of source games will block you from playing them if you have a VAC ban if the same version is used by the other game(Before L4D2 a VAC ban would block that account from games like TF2 and CS:S). But really if you hack you should lose the right to play with others...
Also there is a large worry of what will happen if Valve ever pulls that plug on it. I know that would hurt for me with the 254 games I have on it >_