Hi wsteineker:
I just bought a 15" 1Ghz PB to replace my 667Mhz Gigabit Ethernet Tibook.
I can say without a doubt that the paint job is much nicer on the 1 gig, especially the lighter coloured paint on the side trims. On my old Tibook the top and bottom cases never flaked or bubbled but I had a lot of chipped paint around the Kingston lock, sound out port and combo drive, even though I went to great pains to baby it. I actually never had a problem with paint discolouration or flaking off of the palmrests on either Tibook. I think this may have been a problem with the original 400/500Mhz models but I could be wrong (can only speak from personal experience).
I have heard lots of anecdotes that Apple improved its painting of the tibook ever since the DVI (667/800Mhz) models last spring.
I can certainly say that the quality appears to be a lot better with this current rev. The finish on my new machine is a lot smoother around the sides...so far so good.
However, I still plan on babying this machine just as much as the old one......once bitten twice shy!
One more thing: I have a metal banded watch which I always take off when I use the computer.