If you've sold or lost an iPhone recently, your old device might be sending and receiving iMessages from the old Apple ID despite your best efforts to wipe the phone's contents. Late in October, reports started popping up from users who had lost their phones, wiped them remotely, and transferred their numbers to new devices. Despite the remote wipe supposedly returning the device to a factory-new state, these stolen phones started sending and receiving iMessages from the original, pre-wipe Apple ID. This all happened despite these stolen phones being activated and set up under a new number and Apple ID — iMessages would go to the old phone as well as newly activated replacements.
Unfortunately, it's not clear why this is happening and Apple hasn't acknowledged this issue publicly yet. For now, the only fix appears to be completely deactivating the old Apple ID. For long-time Apple users, this will be a hard pill to swallow, as any App Store or iTunes Store purchases are likely tied to that account. While there aren't widespread reports of this issue, we hope Apple fixes it in iOS 5.1 — this sounds like one of the most un-Apple user experiences we can imagine.