When I ordered my 12" iBook from MacMall, they couldn't confirm its shipment until very late in the evening. So you might just want to check in with them again later today.
Of course, they seem to have installed a bad memory chip in my computer too! I sent it back on Friday and am still waiting to hear when I can expect to have it returned.
Moral of the story: Will never order from MacMall again. I should have just picked mine up at the Apple Store and swallowed the extra cost of RAM and tax. The money saved just hasn't been worth the aggravation.