Steam’s in-client alternative to 3rd party streaming sites is officially live following the latest Steam update.
Steam broadcasting allows users to watch their friends play games by right-clicking names on the friends list and selecting “Watch Game” from the drop-down menu. Doing so will send the friend a request and — pending their acceptance — will initiate the stream. Along with the traditional stream view, you’ll also have a stream chat much like on Twitch and Ustream.
You can check out all of the changes in the latest Steam update on the official Steam news post.