Allow me to clear up some confusion about iMessage that I've figured out over the past few months (please correct me if I'm wrong):

*iMessages can be sent to two different accounts. An Apple ID and an iPhone phone number.

*iMessages sent to an Apple ID are received on every device associated with that Apple ID (a Mac with ML, an iPad, etc.)

*iMessages sent to a phone number are only received by the iPhone associated with it.

*Changing your "caller ID" setting is basically setting which account you want to send messages on your iPhone from: the phone number OR the Apple ID. Just like e-mail, the recipient's iMessage client will automatically respond to the account the message was from (i.e. what the sender set as their "caller ID").

*The iPhone DOES NOT merge threads from the same recipient sent to different accounts. So if the sender sends you one iMessage to your phone number and another to your Apple ID, you'll see two different message threads.

Setting your caller ID to your Apple ID gets you most of the way there. Any iMessage that you initiate will cause the response to be sent to your Apple ID instead of your iPhone's phone number, which will show up on all associated devices. However, if the other party initiates the conversation, and they send the message to your phone number (because that's all they have in their address book, or they manually enter your number in), then you'll see a SECOND thread for that user.

Also, if you do manage to successfully get a conversation going with another iMessage user on your Apple ID and the other party's phone does not have data coverage, their iMessage client (unless this is toggled OFF) will fall back to SMS. The SMS message will be treated like an iMessage to your iPhone phone number, so you'll see a second thread if you already have one going on your Apple ID.

Hopefully that adequately describes why so many users have so many problems with iMessage. Here's what Apple needs to do (why this wasn't done at the launch of iMessage is beyond me):

1) Merge all iMessage threads by sender. The user shouldn't have to care about where the message was sent, which is something hidden from them anyway. Whether it's an iMessage sent to their phone number or to their Apple ID or a regular 'ol SMS message, that should all be one thread.

2) Push/sync iMessages sent to an iPhone phone number with the associated Apple ID. Apple has this information linked. There's no reason that an iMessage sent to a phone number shouldn't be treated the same as an iMesssage sent to an Apple ID. At LEAST give us the option.

3) Allow the iPhone to act as a sort of SMS proxy. Any traditional SMS texts that are received should be pushed back up to Apple and synced with the user's Apple ID. Any response to that SMS from a non iPhone device should be sent as an iMessage if the recipient is capable, or pushed to the iPhone for sending as an SMS. Or Apple could send the SMS themselves. This would end any remaining possible confusion that isn't already solved by 1 and 2.