I apologize if this has been answered before - but as far as I could tell it's been asked several times but not answered...
I have an Apple Magic Trackpad - it does pair fine with the Playbook, however there is no way to distinguish "right clicking" so none of the gestures work You can move the cursor around just fine and click to select/highlight things with the equivalent of a PC "left click".
So it wouldn't work that well if the PB was far away from you / hooked up via HDMI to your TV.