To go along with the iOS update to BBM from earlier today, BlackBerry has also pushed out an update for BlackBerry 10 users, For some folks, it's not going to be a new release as it it appears this version might have came with 10.2.2 if you loaded that. However, most folks should be seeing v10.3.43.9 provided you're running 10.2.1 and not some other leaked or developer build. Long story short, if you're running a stock device, you should be seeing an update. If you're not running stock, you may already have it.
As for the changes, well it's all the things that were in the previous BlackBerry Beta Zone build such as the new add contact screen, where you can choose PIN, Email, Barcode, SMS and even invite folks from your address book to download BBM. On top of that, there's also additional support for BBM Protected and the usual 'bug fixes and improvements'.