None
Website Inner Bits has said they can confirm that prototypes of the Sixaxis controller with rumble capabilities are currently in the hands of “various Sony developers” and that “an official announcement and unveiling is expected in the next two to three months.”
The website is also claiming that “new versions of the Sixaxis controller are quietly replacing the original controllers launched with the console.” Apparently, the new controller has improvements in the motion sensing department as “Sony has improved the fidelity of motion sensing in the controller. The original controllers apparently suffered of too much of a dead zone.”
More on this as news becomes available.