Originally posted by WDMcM:
Actually you could use a product by Moog called the PianoBar. MOOG Music PianoBar
This device sits at the back of the keys on any acoustic vertical or grand piano and generates MIDI note and velocity data. This data is then used by the PianoBar module to access the internal sounds and also to control external MIDI equipment.
What's another $1495.00 for the pleasure of playing a real piano while still being able to use an arranger keyboard or module? 
Dave
Ha, ha... good reply and good thinking - except that the arranger hasn't been made that can follow a real pianist and probably never will be. Thanks for reminding me about the PianoBar though.