Valve announced Steam OS today. It's the Linux-based software that will run their living room ecosystem.

They also teased two other announcements in the immediate future. They will be:

1. The new Source game engine. Along with the announcement of the engine, they'll announce their launching titles, Half Life 3 and Left 4 Dead 3.

2. That will lead into their second announcement, the Steam Box.

This is my prediction.