The second part of the Valve's announcement is centered around how the hardware for the new "Steam Machines" and the chance to become one of Valve's prototype beta tester.  The Steam Machines will come in multiples types depending on manufacturer of the hardware.   Valve want the users to choose whatever hardware that meets their needs.  They are looking at 2014 for the the first Steam Machines to be brought by Valve's partners in development.          Valve also released information on how to get into beta tester pool for their own Steam Machine Prototype.  To be eligible to participate you must complete a Quest on Steam.  

There will only be 300 beta testers chosen.  The Hardware Beta Eligibility Quest will be Locked on October 25th.    

THE HARDWARE BETA ELIGIBILITY QUEST:

Before October 25, log in to Steam and then visit your quest page to track your current status towards beta test eligibility.  Prototypes are planed to be shipped this year.

1. Join the Steam Universe community group

2. Agree to the Steam Hardware Beta Terms and Conditions

3. Make 10 Steam friends (if you haven't already)

4. Create a public Steam Community profile (if you haven't already)

5. Play a game using a gamepad in Big Picture mode

     Source: Steam Machines 

A FAQ was also published to answer some questions.