Hi all,
We just added Steam lobby support, meaning when a friend is in the lobby stage of a game, you can connect by using the "join game" option on the Steam friends interface.
Things to note:
You can only join games when they are in the lobby stage! Once a game starts it cannot be joined.
NAT traversal isn't complete yet, so if you are behind a router, you have to forward the port 26999. If you are having trouble getting people to connect to you as host, try with someone else as host.
Enjoy!
Dan