Pre-orders for the Motorola XOOM Wi-Fi have started over at Costco and Amazon, but one of them will set you back $10 less. Costco is offering it up for $589 and also tossing in a gel case to help protect your beautiful new 10″ investment. Anyone jumping on this? If you need more info, we wrote up a Motorola XOOM review that I highly recommend you check out. Just ignore any 3G talk in it.