Just to warn folks, there is no known secure way to wipe the iPhone. Even the article and the link to the "paranoid wipe" don't have a real system, at least not one that has been tested in anyway. If I was a betting man I would bet that someone out there is buying up iPhones with the idea of looking for personal data and then reselling them. If you read up on how much you can recover you'd think twice about selling the iPhone to a stranger without a proven method to securely wipe your old data.
At the very least read this article about wiping the iPhone, which was written by the guy who wrote the scary forensic tool for the iPhone.
At the very least read this article about wiping the iPhone, which was written by the guy who wrote the scary forensic tool for the iPhone.