- SteamOS 1.0, Valve's first Linux-based gaming distribution focused for consoles, is based upon Debian "Wheezy" 7.1. It will surprise many that it's not directly derived from Ubuntu (Core) but rather is being based upon upstream Debian.
- This first SteamOS beta is codenamed "Alchemist."
- SteamOS 1.0 back-ports the NVIDIA and Catalyst binary drivers so the fresh drivers are running on Debian rather than their aging drivers in this stable release series. The Mesa support was also back-ported.
- GNOME is hiding behind the Steam Big Picture interface in this first developer beta build of SteamOS.
Many more details and the initial SteamOS Debian packages can be found from this SteamOS directory. At the moment the ISOs don't appear to be public yet.
UPDATE: More details here.