After BlackBerry's BBM for Android rollout was abruptly halted two weeks ago, even before the app was officially listed on Google Play Store. All this was caused due to overloading of their servers, which again happened because of the large number of BBM activations done using a leaked APK of the software.
The new BBM Beta for Android packs a UI which is slightly different from last time. Also, the persistent notification is now optional (life saver). No word on a final release date as of yet.