According to the latest update on the Steam Linux blog :
I think they ought to make their own distro as well.
Things have been going well. We will be having an internal beta starting next week, and a private external beta for 1,000 users sometime in October.
The private external beta will include:
Steam
One Valve game
Support for Ubuntu 12.04 and above
It will not yet include:
Big Picture mode
Additional Valve games
For existing Linux users, the external private beta is a good release for seeing where we are in running our games on Linux. We will be using a sign up page for the external beta. Information about the sign up will be announced in a future post.
For those new to Linux, we recommend waiting for a subsequent release where more features are implemented along with improvements to the user install experience.
I think they ought to make their own distro as well.