The native Facebook client for BlackBerry PlayBook also updates on launch of PlayBook 2.0! According to change-log it fixes some unknown bugs but the portrait feature is the best upgrade here. So if you have a PlayBook & getting a notifier for update, Just Do It!
Download Facebook for BlackBerry PlayBook >>
I saw the following changes in new version of Facebook on PB (which I think is great as I always wanted them, now just like for comments are missing):
1) Facebook screens work also in portrait orientation mode now (including the pictures).
2) App takes advantage of Facebook’s new Messages feature that displays the full conversation history of the messages and chats.
3) You can delete your Wall posts now.
4) Mutual Friends are viewable now.
Addition: Facebook apps for PlayBook now has predictive text/ spell correction support. 😀