The G4 iBook is a must. If not soon, then eventually. You see the whole digital hub thing here depends a lot on altivec for video rendering and MPEG transcoding for DVD. Even though I don't have a real need for a mobile unit, I would plunk down the cash for a G4 iBook since it would be able to render video transitions faster than a snail, unlike the current the iBook which is a very nice internet, eamil and WP machine.
The iBook has a very nice form factor with its compact size, good battery, and outside of video it's snappy enough to be considered a good machine. Drop a G4 in there and it's a serious contender against the tiBook, which hopefully will be replaced soon by a G5 powerbook (I'm guessing MWSF optimisticly).