The Beta has just been updated with the following changes: SteamVR
Added new Desktop Game Theater support, run any of your normal desktop games and have them appear on a giant virtual screen in your headset. Any game that supports Steam Broadcast should work with this feature, some tuning of the games graphical settings may be required for the best experience. This feature is currently in beta and can be accessed by adding "-vr2dgames" the command line when launching Steam.
Fixed Steam not quitting correctly when shutting down SteamVR at the same time
Added icon in the Library view in the Steam Dashboard to show which games support motion controllers