What Apple has done is merge all addressed/phone numbers of an AppleID into one. If you send a message with Messages on you phone, your side of the conversation will appear in the thread on your phone/iPad/etc. They are one now.
So, people can iMessage you at any of the identifiers attached to you AppleID and it will be sent to all locations.
So, people can iMessage you at any of the identifiers attached to you AppleID and it will be sent to all locations.