Have you seen the
Buyer's Guide over at MacRumors? I think this is a great way to check out product update probability and use it myself periodically. The iMac may be due for an update soon, but my guess is that it won't happen until MacWorld Expo at the earliest in January since Apple just updated the notebook lines yesterday and it's not typical for them to do any other updates before the holidays. Can you wait until January? If not, go ahead and buy one now - I'm sure you'll love it!