I called yesterday, and the guy said that he thought the store manager was just guessing, and that he had only heard that the 16 gig would be available. And then, rather sheepishly, said that he only knows what he reads online, and that AT&T is being really cagey with the launch details, and that only the online sales department is being given information about only the online presale which is only for the 16 gig.
Fingers crossed they'll have at least a 32 gig at launch. I was going to buy off contract and then sell it whenever a 32 became available, but if they sell them at launch, may sign a new contract (mine's been up for over a year).