Game streaming, one of the most interesting features of the upcoming SteamOS, will be arriving first for the regular Steam clients.
For now it's called Steam In-Home Streaming and, from what Valve is telling us, it will probably be one of the most interesting features of SteamOS and Steam Machines.
“Steam In-Home Streaming is a feature that will allow people to stream games from one computer to another anywhere in their house. This feature will be available for beta testing later this year. Beta participants will be randomly selected from members of this group, so join, have fun, and stay tuned for more details!” reads the announcement on the official Steam group.
Unfortunately, as you can see, only a select few will receive this feature, but history has shown us that it will soon be available for all.