You've probably already guessed that there's some pretty tight integration with Mountain View's other virtual properties, including Calendar, which means that sending your friends or coworkers a "save the date" to brunch or brainstorming no longer requires clunky email, or a phone call.
It's unclear whether Google intends to integrate the Meebo Bar into its own online properties, or whether the Mountain View giant simply views it as a method to increase its advertising reach.