Valve announced today that its new in-home streaming feature, which allows you to stream games from a "main" computer to any other rig in your home, is now available to all 75 million Steam users. Previously, the feature was only available to some users in beta.
One of the main benefits of Steam in-home streaming is that you can play your PC games on a lower-spec computer because they are not actually running on that rig, only being streamed to it. Video and audio are streamed from your main computer over your network.
Steam's in-home streaming service also works across platforms, allowing you to stream from a Windows computer to a computer running OS X, Linux, or SteamOS. In the future, Valve says it will allow OS X, Linux, and SteamOS machines to host streams.
Using Steam's new in-home streaming, you could also hook up your laptop or low-end PC to your TV and stream games to it using Steam's Big Picture mode.