i just got that too, wanted to see what it said. if you look below the add to wishlist thingy it says email me when back in stock. i think they are so far behind in the PTs that they are no longer taking any more orders on them until theyre caught up. it makes perfect
sense to stop offering something they cant give a reasonable time frame of fulfillment on. it would be far worse business to do that than to simply say they arent taking any more orders on an item. very smart, and better for their relations with their customers, even though it may be a little painful to both parties, the sting is less than the alternative.
edit: just checked and this is only for the 510. IMO, they should update their homepage to say something about that.