As someone who worked in visual design for years, and who has owned a Macbook (white), Macbook (black), MacBook Pro, and now Macbook Air, I can definitely say that I prefer the Air's approach the best. The silver is just right. I found the white distracting in some situations and the black of the Macbook Pro distracting in MOST situations.
Someone mentioned overall design- my trained opinion would be that there is a gounding problem visually with the current Macbook Pro with black bezel. What I mean by that is, in that design, what you have is a black bezel and black hinge that make the display portion of the machine visually "heavy", whereas the silver with black keys does not do enough to ground the machine. Basically, it needs more black somewhere on the unibody. Since they've debuted, I've wrestled in my mind with what could be done to remedy this - a black trackpad would look out of place, the only option would be to make the flat edge of the bottom black (around the ports, thumbscoop, etc). You can try this yourself by putting on a black Speck case on the bottom if you have a MBP. It's better grounded visually, but once closed looks a bit silly of course with a silver lid, and would look worse with a black outer enclosure entirely and silver palmrest. So, the options they had were what you see now (not a bad design by any means), or an all black option - which I would have chosen were I Jonathan Ive.
Similarly, the first Macbook Airs faced a smaller grounding problem when opened. Their silver bezel, silver hinge, silver palmrests, AND the small silver rubber band that seals the bezel to the top lid made the black keyboard too overwhelming. Apple seemed to have realized this in the current iteration and solved the problem by simply adding a black hinge and black rubber band/ bezel border. The design looks damn slick in my opinion and the best of Apple's portable Mac designs.
Apologies for the long post- design is my passion with Apple!
