Even though most AT&T stores sold out of iPhones on the first day, many Apple stores still had them in yesterday (as well as today). So why are people putting up iPhones for $700-$900 on Craigslist? And why are auctions on eBay ending at higher than retail?
It's hard to say. Looking through completed auctions on eBay, you see lots of phones selling for around $650 with free shipping, which means you're getting a phone for just about retail. There are a few that went for crazier amounts ($700+), but those are pretty rare. So it looks like a buyer's market on eBay. If you live in a state without an Apple store, you can definitely score one here for close to retail.
Our guess is that on Craigslist, where you can't see completed listings, has a similar story. Especially here, in San Francisco, where there ought to be tons of Apple stores and tons of stock. Why would someone meet up with a stranger just to get a phone that you can hop down the street and get one from an Apple store?
This is of course moot if you have the patience to wait 2-4 weeks to get one from the online Apple store. Those seem to still be in stock as of right now, but ships in 2-4 weeks, which is way too long for most geeks to wait.