Research in Motion has released a beta version of the next major update of their BBM app.
The app now feature voice calling support over Wi-Fi which means you can now call friends without using your cellular minutes.
There are some other improvements as well. You can see which users are available for voice calling. The phone features are available during the voice call so you can still chat or check other sections on the phone.
BBM 7 Beta is available from the BlackBerry Beta Zone.