Although RealID may be optional on Blizzard's World of Warcraft forums, in the newly-released Starcraft II the RealID system is going to power social network-like features. Using RealID, Starcraft II players can connect with their real life friends playing any Blizzard game on any server. Players will also be able to post status updates to Blizzard's Battle.net online service using a feature called Broadcasting. Any RealID friend will be able to see the status updates. 

Users will be able to connect their Battle.net accounts to Facebook in order to quickly add real life friends who play Blizzard games to their RealID network. This is currently the only way that Starcraft II can connect to Facebook. In the future, Blizzard hopes to add the ability to post in-game accomplishments to Battle.net and, possibly, Facebook itself. Users can also add Starcraft II players to their network who aren't using their real name as part of the RealID system at all. 

Networked players who are all playing Starcraft II will be able to form parties and voice chat with each other as they play the game, regardless of which game mode they're playing. When full Facebook implementation is added to the system, players will be able to record gameplay videos and share them through social networks. Starcraft II features extensive support for achievements, which can be displayed as part of their Battle.net profile.

[via Inside Social Games]