Sorry to pull out the "golden shovel" and dig this thread up, but I have the white spot problem on my 12" iBook which I bought in January '05. Any time I bring up a white screen (e.g., in PhotoShop, Pages) you can see these splotches across the bottom third of the screen, with smaller ones elsewhere on the display.
The Genius at the Apple Store looked at it for about 15 seconds and said "Yeah, this is wrong. We'll send it in for you." Now, the Service Depot says they can't reproduce the problem and they want to send it back to the store as "no problem found." After a few minutes on the phone with the Apple Customer Service rep he took down some more info to add to the service ticket and claims they'll look at it again.
Meanwhile, my aggravation grows.
Does anyone know any more about the white-spot problem as it relates to iBooks, or am I just experiencing a one-off?