That's what I am trying to find out, and worrying about. And whether if it is already supported or not? It should be a simple matter as a software driver (generic Bluetooth HID keyboards) to support keyboards.
Some people may say it is security concerns of tapping into wireless signals. But there should be absolutely no security differences between headsets and keyboards (It's simply wireless sound versus wireless keypresses, encrypted equally in the same way with BlueTooth) and meaning, no reason for RIM not to support Bluetooth keyboards;
It is wonderfully convenient for those occasional marathon mammoth-sized emails, and provides yet another reason to leave that laptop behind. :D