Same here. I was foolish and paid for the game before browsing the forum also. I seemed to remember having this exact same problem when the first version of Flaming Cliffs became available. It took days to finally receive my serial number! I just don't understand why the serial number can not be included in your intial purchase e-mail. I have a transaction ID and a receipt of purchase but, that's it. No serial number included with my purchase!
This is extremely frustrating and might I add, a terrible shopping experience. I'm just inpatient and want to fly like the rest of you guys.
For the record, my purchase screen looks nothing like what Nate posted. =(