My guess is that coming iBooks will match the new generation of iMacs. Does anyone remember at what point iBooks were made white? I would have to guess that it happened when snow iMacs or the new iMac debuted. My speculation does, of course, assume that the coming iMacs will feature a major redesign (or at least color change).
Regarding the PowerBook, I'd have to say that I'm pretty satisfied with the current design. Granted, I haven't come to love my 12" PBook the way I loved my iBook (perhaps time will do the trick), I am a fan of the aluminum enclosure. I suppose I am a little worried about dents and the like, but when I have the computer in its carrying case, I toss that thing around without a care. I suppose I would like to see something even smaller than the 12"; though the 12" may fall under the "ultraportable" category (of course it is "thin-and-light"), the idea of a 2-3 pound laptop with an even smaller screen sounds great to me. And I believe I would be willing to sacrifice an optical drive and some ports and speed to achieve such a small form factor. You see, I use my 12" PBook at work for web design without much problem, so I'm thinking that I could get away with something even smaller for taking care of such basics as internet/email/Office programs, etc. Built-in wireless and Bluetooth would of course be necessary.
In terms of design, keeping with metal would be good. But whatever makes it lighter is fine with me. If we're talking ultra-thin ultra-strong ultra-light carbon fiber (is it?), that sounds good to me. The current price range I think is good. The ultralight I described I would expect to cost as much as the 15" PBook, but the thought of a 2 lb. notebook is pretty cool in my mind.
Mike LaRiviere