This was not announced by RIM with the recent OS update but 3rd party apps including Facebook for BlackBerry PlayBook work now when you have it connected via bridge. This means you don’t have to have Wi-Fi connection to use your PlayBook. I tested this as soon as Poky from BlackBerry India told me about it. Facebook, and Blaq worked as soon as I opened the apps. I know it works because I am nowhere near a Wi-Fi connection. The regular browser also works. Not sure if RIM did not mention this because they did not want to make the carriers mad or it is a glitch. I think this is really awesome the fact that it works and I hope they do not do away with it.
Let us know if yours also works over Bridge?