Valve seems to put a lot of effort into the SteamOS Brewmaster branch, which is based on Debian 8, although it's not giving any indications that it wants to migrate to the new version before the Steam Machines are launched.

The Steam Machines are the new consoles made under Valve's guidance by a number of third-party hardware companies like Alienware, for example. The launch date was set for November 10 a long time ago and Valve is not budging. In fact, developers have been working to keep both branches of SteamOS active, although the one based on Debian 8 seems to get more attention.

Valve developers said a while back that they didn't intend to make Jessie (Debian 8) the start of the SteamOS just yet, and most likely the Steam Machines will launch with the regular edition. The problem is that SteamOS based on Debian 7 is hardly updated anymore, with the exception of a few drivers and such. Either the OS is just as they want it or they will try to ship Brewmaster as default and dump the old version entirely.

SteamOS Brewmaster is not unstable

To make things a little bit more complicated, there are two branches of SteamOS Brewmaster, one deemed stable and one Beta. Today's update has been made to the Beta branch, and it will probably land pretty soon in the stable branch as well.

According to the changelog, a number of security issues have been corrected with Iceweasel and cyrus-sasl2, and the auto-repair service has been improved. If you haven't heard of this auto-repair service, don’t worry, you're not the only one. This is a tool that will help users who experience problems restore their OS if something goes wrong. It's not clear to what extent this tool works, but the fact that it's getting improved is a sign that it's not all that good to begin with.

You can download Steam Brewmaster from Softpedia and give it a go. Please keep in mind that it's not a LiveCD, and you will need an entire partition in order to install it.