The controller would essentially disassemble into two pieces and would each contain an accelerometer for motion sensing-functions. If you can't beat 'em...
This would effectively allow Sony to tap almost directly into the Nintendo Wii audience but with the huge advantage of raw power of the PS3 over the Wii. According to sources working versions of the pad have already been handed out among certain development partners, there's no idea when Sony will officially unveil their plans.
The PS3 already had a motion sensing controller but was short lived, the SIXAXIS, but the more popular 'rumble' feature had to be sacrificed - a position that's now being reversed to the glee of many PS3 gamers. Hopefully Sony will let this all come out of hiding this E3.