RIM has announced the availability of BBM 7. After a month of beta testing the new BBM 7 is ready to go. Its most impressive feature is free WiFi calling between BlackBerry users. You can now switch from text based messaging to voice calling over WiFi for free. Check out the video for a demo.
There are a few other features like in app notifications of updates, profile, groups, and contact syncing with your BlackBerry ID and more.
You can download your copy in the BlackBerry App World. It runs on all BlackBerrys running OS 6 and above. RIM says they will make it work with OS 5 devices at some point in the future.