The story so far: In the last two weeks, Valve has announced SteamOS, an open source Linux based gaming systems, the Steam Machine (also known as SteamBox), a gaming console running on SteamOS, to compete with Xbox and PlayStation + the Steam Controller, a gaming controller, specially build for SteamOS and SteamBox, to provide a good gaming experience to the users.
Also 300 SteamBox beta units will be sent for free to some lucky gamers, in order to do some testing and collect feedback. More information about how to get in Valve’s trial can be found here.
Worth mentioning is that the Valve Steam Machine will come in various models, with different hardware specifications.
Current news: The hardware specs for the first 300 units that will be sent with testing purposes have been officially announced:
Graphics: NVIDIA GeForce GTX Titan, NVIDIA GeForce GTX780, NVIDIA GeForce GTX760, NVIDIA GeForce GTX660
Processor: Intel i7-4770, Intel i5-4570, i3
Memory: 16GB DDR3-1600 (CPU), 3GB GDDR5 (GPU)
The first Steam Machine models come with Intel CPUs and NVIDIA CPUs, but I think Valve will also release SteamBoxes with AMD and ATI components, since the ATI Radeon GPU has very good support on the Linux systems.