I hope someone will try this, but here goes:
There is no G5 notebook, but there's the all in one G5 iMac. The G5 cannot be put into a laptop becuase it is too hard to cool; I beg to differ. If you rearange the components, you'll probably be able to fit in a laptop case similar to the Dell XPS, or another large case. It will probably also be a multimedia portable, buz it ain't gonna be no raod warrior with a 17" scrren
PS the power supply would pose a small problem, but if the iPod can have new batteries, i think you can find one for the G5. The iPod wasn't meant to be opened, the iMac G5 is, so that the use can upgrade the memory.