A big thanks to everyone who's posted on this thread, particularly the folks who wrote the Python program!
I've had the Python program running in a Terminal window since last night and it's been checking local Target inventory for all 64GB models every 10 minutes since then. This morning at 10:35
I got notified that a local Target had stock black 64GB AT&T iPad 2's (exactly what I was looking for), so I jumped in the car, and sure enough, they had 'em! I bought two of 'em and asked the security guard (who was stocking the cabinet for whatever reason) how long they lasted once they got stock. She said "they don't." She also told me that they'd only had them for about 30 minutes and that's about how long it took for me to get to the Target from my house.
FWIW my Target was only selling one per person so my wife and I bought one each (and yes, we have jobs, we're just off work today).
Thanks again! I'll now cancel my Apple Store order and my Best Buy pre-order!