Cameo 'Potter' Role for Robin Williams?

Harry Potter and the Sorcerer's Stone
An inside source for SFGate reports that Robin Williams will have an uncredited cameo in "Harry Potter and the Sorcerer's Stone." He and the film's director Chris Columbus worked together on "Bicentennial Man" and live near each other in San Francisco.
Robin Williams last uncredited appearance was as evil incarnate in "The Secret Agent," adapted from another Conrad novel. Aren't we literary, dropping his name twice.
Thanks to 'Don' for the heads up!