Taking part in the BBM beta? If so, you're going to want to fire up the BlackBerry Beta Zone and grab the latest version which has now been released. According to the change log, this update doesn't bring any huge additions but instead just covers bugs fixes and stability improvements based on the feedback received.
This latest version of BBM includes more bug fixes to improve stability and performance. It builds upon the last beta version, which you have considered as a very solid build from your feedback.
The update is live now in the BlackBerry Beta Zone, so if you've been invited, go ahead and get it downloaded. You can also let us know in the comments if you happen to spot anything that might not have been mentioned in the release notes.