Here's an interesting concept.. you can now stream your Steam games over your network to other computers. Everything is rendered on your "main" computer and then sent to whatever other computers you want. I don't see much of a use for this since if I'm going to game, it'll be on my main PC and not a laptop, but for other people this could be handy. I'm sure the hardware requirements are pretty stiff for optimal performance.
http://store.steampowered.com/streaming?snr=1_41_4__42
http://store.steampowered.com/streaming?snr=1_41_4__42