Earlier this week, we found the story of an Oregon State police officer who was able to retrieve email, photos and other bits of information left by the previous owner of his refurbished iPhone. Granted, he was using special forensics software, but the data was retrievable.
Geeks to the rescue! Securosis offers up a method for ensuring that all personal information gets overwritten. It involves the clever use of playlists, but you'll have to read the whole post to get all the details.
Now, they admit to not testing this method thoroughly, so if any of you iPhone hackers out there want to put it to the test, please tell us what you find!