Valve have today announced a brand new feature hitting Steam, Steam Broadcasting. It’s curently in open beta, and despite what you may think, it’s a system that doesn’t output to external streaming services (i.e. Twitch/Hitbox etc.), but internally to Steam.
The way the system works is that you’ll need to have the latest Beta client to start streaming, with anyone wanting to watch will either need said Beta client, or logged into to Steam via a web browser (currently both Chrome & Safari are supported). From there, friends can click into your profile (or hit a “watch game” button in the drop down menu in the friends list), to which the stream will start proper. From there, you can choose to set it to friends only, or enable it so anyone can watch it. Broadcasts can also be shared onto a game’s Steam Community page, allowing more people to get eyes on it.
At the moment, the Beta is limited to Windows 7/8 machines, with Linux, Windows Vista and OSX support coming in the future.