I actually just ordered the Freedom Pro Bluetooth Keyboard that works with both the HID bluetooth profile and the SPP bluetooth profile.
The Thunderbolt uses the SPP profile.
This keyboard works really well except for a few qwerky placements of buttons. For example the shift key is an extended reach for the right hand. 9 times out of 10 I end up hitting the up button and then I am typing in the line above.
Also,not all the shortcuts work, but I am sure a software update will eventually fix this.