A significant security hole in iPhone OS 3.0 may have surfaced, as a recently published YouTube video demonstrates how the Spotlight search cache doesn’t sync message status with the mail client, so you can still pull up old messages with Spotlight if you know the subject line. According to Engadget, user Matt Janssen, who discovered the bug, says he’s been able to pull up emails three or four months old. Current rumors state that the bug is fixed in iPhone OS 3.1, but until then, here’s the video: