San Jose Mercury News was the first to report that emergency services had been called following reports that a member of staff had happened upon an envelope full of white powder in the company lunch room.
Fearing the worst (an entire team of Apple developers wiped out), they sent along some people in hazmat suits to sort things out. The building was evacuated lest anyone get tempted to snort anything and the team went inside to check things out. Mercury News reports (citing Santa Clara County sheriff's Sgt. Don Morrissey) that preliminary tests revealed the powder was not a hazardous substance. It was then taken to a Santa Clara County lab for more testing.
The Register reports that authorities viewed security tapes of the cafeteria in an effort to determine how the envelope got there in the first place. Apparently the tapes didn’t help and they still have no idea whether someone left it there on purpose or just forgot to bring their envelope of flour/cocaine/anthrax with them when they were heading back after lunch.