Follow the money and find the largest short seller in the aftermoon. That person is in on the email.
Slashdot | Fake E-Mail Results in Angry Apple Shareholders "Apple stock dropped 2.2% today in mid-afternoon trading as Engadget published news based on a faked e-mail inside Apple. ‘Apparently an internal memo was sent to several Apple employees–and forwarded to Engadget–around 9am CT today saying that Apple issued a press release with the news that the iPhone was now scheduled for October, and Leopard was delayed until January. About an hour and a half after that e-mail went out, a second e-mail was sent–this time officially from Apple–saying the first e-mail was a fake, and that the delivery schedule for the iPhone and Leopard had not changed.’"