First of all Steam for Linux is now available as open beta! → Just take a look at this.
Additionally I found a great tutorial about running Steam for Linux on Debian Wheezy/Testing x64. → Grab it here. I didn't test it because my PC still isn't reassembled but I'll give it a try.
That's all. I'm gonna enjoy my Ramen now.
There's another good way for running Steam on Debian Linux. Follow → these instructions created by the Steam for Linux Community and try one of their scripts. I've been using → Kano's script (yes it's made by the guy who created Kanotix) and it works flawlessly. Next year I'm trying to buy a Linux game. Maybe SS3.