The biggest addition is the ability to make free voice calls to fellow BBM users over wi-fi connections - but apparently not 3G, at least for the moment. BBM 7 also adds a split-screen 'multitasking' feature, which enables users to access BBM's other functionality, or other apps entirely, while on a voice call.
“BBM began as a convenient and effective business messaging tool, and today it is an essential part of daily communications for customers around the world," said T.A. McCann, RIM's vice president of BBM and social communities. "Now, with BBM 7, customers have a new option. They can text and talk with their BBM contacts near and far, for free.”
It's part of RIM's ramping up ahead of the launch of BB10 next year, which has also seen the SDK Toolkit, for developers creating apps for its new platform, reach its final 'gold' build.