Steam Link Anywhere extends the ability to connect to your PC and play games remotely via the Steam Link hardware or app on a supported phone, tablet or TV. Now, you'll be able to connect to any other computer running Steam and play games remotely via the internet, too.
The feature is described as being in early beta still - only those with beta firmware will see it at present. Valve warns you'll need a good connection.
Second, Valve is opening up its servers so any Steam game can use its own private network for game traffic, for free. This is the network Valve built itself to run multiplayer games like CS:GO and Dota 2.
Both are solid, interesting features with a lot of potential. Neither involve the topic many want Valve to discuss as GDC approaches.