The first round of 300 beta Steam Machines and controllers ship out on Friday, December 13, Valve announced. Selected beta testers will be notified today around 5PM ET. These anointed ones will find a few games running on SteamOS in their libraries and badges on their Steam profiles marking them as participants.
SteamOS will go live once the hardware ships on Friday, downloadable by individual users and commercial OEMs. Additionally, the in-home streaming beta will begin soon, Valve notes.
Steam Machines are due to ship commercially in 2014. Expect more information about Valve's hardware initiative at CES in January.