This post in the PlayStation forums claims that Sony Customer Service told the owner of a bricked PS3 that plugging his console into a surge protector had voided his warranty, and that he'd have to pay $150 to have the unit repaired.
This sounded pretty unlikely to us, so we contacted Sony and were told that, no, plugging your PS3 into a surge protector does not void your warranty. Duh. Ok, they didn't actually say "Duh," but it was clearly implied.