Valve begins sending out invites to its in-home streaming service

Valve has begun sending out invitations to Steam in-home game streaming, which will allow gamers to stream any game from one PC to another, as long as both PCs are on the same network.

This might not mean much to those who have Steam at home, but when Steam Machines roll in, this will be a very big feature. You can have your massive Steam library on your main PC, and simply stream whatever game you want to play to your freshly unpacked Steam Machine. This will save transferring tens of gigabytes of data across, or worse, re-downloading those massive games.