Bubblegym is to my knowledge the first tilt-sensitive game for notebook computers. When Apple revised their Powerbook line earlier this year, they added Sudden Motion Sensor (SMS), a detector that is used to protect the hard drive if the machine gets dropped. Chances are, they probably weren't expecting it to be used as a video game controller...
Finally, Bubblegym now runs natively on all Apple notebooks equipped with a Sudden Motion Sensor. That includes all MacBooks and MacBook Pro laptops. And of course all iBooks and Powerbooks released after March 2005.