I hear that even with a restore, some personal data and info still remain on the iPhone. Before I sell mine I would like to be able to completely remove all personal stuff. Is there a way to do it for sure?
Supposedly that way doesn't work 100%. I read (I think it was on here), something about doing a full restore, and then creating playlists that take up all of the free space on your phone. Syncing them so the phone is full and then restoring again, thus whiping all your data from SMS, email, etc.
My understanding is this is the most thorough one. It's based on the method put forward by Nervegas, who is the iPhone dev / security guru who has worked with law enforcement agencies and proved data recovery vulnerabilities on the iPhone after normal restores etc.