I remember someone posting a while back (either here or at MacRumors) that a good way to tell if something was going to be updated is if it was (not) on the Hardware page @ apple (
http://www.apple.com/hardware/). Well the 15" is back. This may be becaues the 12" and the 17" can't both be there-- because of the new eMac update... but it is worth noting.
[edit] Well I'm an idiot. It appears that it is a random changing image between all three-- the 12" the 15" and the 17".