A few of my friends are having this problem. First off, I have a MacBook Pro with Leopard. Here's the deal: When I add contacts to Address Book, and then sync my iPhone in iTunes, Address Book doesn't transfer any contacts I added to it (Address Book) since my last sync. I have verified that the "Sync Address Book Contact; All contacts" setting(s) are turned on in iTunes when I have my iPhone connected. Furthermore, when I add contacts to my iPhone and sync, they are ALWAYS added to Address Book. Too make it short: Contacts added to address book - NOT transfered to iPhone 3G Contacts added directly to iPhone 3G - ALWAYS transfered to Address Book. Any assistance would be great. Since a few of my friends are having the same issue, I am guessing this is a simple setting related issue or something along those lines.