Yea, I've been trying to figure that out as well. I ordered my set through Walmart.com who now says they haven't recieved them yet. So much for my 7-2-2003 scheduled delivery
What sucks is I've talked to a few shops overseas and its released and available to the public. I can't understand how they are able to sell it and all the stores here are saying the 18th.
I heard they decided to release the books like their miniatures. Some stores will get all Player's Handbooks, while others will get the "uncommon" DMG and some will get the "rare" MM.
Looks like you'll have to visit several stores to get the books you want...