"I think Apple still uses MOT G4 chips for a number of machines, so this gets 'interestinger' "
As it is all current Powerbooks, the eMacs and the iMacs as well as the xServers, it does look more than "interesting".
The xServers are obvious targets for the current G5s so that can be disregarded. Low numbers sold and fan noice not an issue.
The iMacs (and later eMac) can house a G5 be it with some tweaking of the cooling. They might have do do drastic things like having to increase the size of the iMac or put the powersupply in a brick like the cube, but it ought to be posible to do.
The Powerbooks on the other hand are far more tricky as they have severe constraints in size, heat dissapation as well as power consumption.
I have previously have made the remark that buying G4 is an investment in a dead end and a G5 in the future, it seems like the end is getting closer
