People
This is cool. Log in to your online networking sites (right now I’m using Digg, Facebook, Pownce, and Twitter) and it will consolidate all your contacts across all those networks and will notify you as soon as someone changes something on their account. Very handy for following a prominent Digger, for example.
It also has some basic features so you can use the sidebar to view media that your friends have uploaded as well as interact with them (message, share a link, and other things like that).
Great intro to Flock – well done!