It's official:
A850 - $2k 24.6 mp Full Frame. In-body IS.
A500 - Both fast focus and main sensor Live View on 3" tilt up/down LCD. 5fps. 12.3 mp. In-body IS.
A550 - As 500 with High Ress LCD and 7fps with constant focus/exposure. 14.2 mp. In-body IS.
TF