I have Steam and TF2 working on openSUSE 12.2 64bit, KDE 4.9 and Catalyst 12.10. I had to fix the symlinks for /usr/lib/libGL* and install some 32bit libraries. libnsssharedhelper0-32bit, libpng12-0-32bit, libpng14-14-32bit, libasound2-32bit, libpulse0-32bit and maybe a few others. In order to get the sound working in TF2 I have to launch Steam with:
I'm not in the beta and I haven't had any trouble playing TF2. I have to turn off compositing in KDE to get it to run smoothly. I did not try to use the mic yet.
export SDL_AUDIODRIVER=alsa; /usr/bin/steam %U steam://store