Apple really needs to wake up with regard to it's Powerbook line...
First of all, the graphics system is WAAAY underpowered for what you pay. Apple touts these machines as mobile workstations, but unless you are doing print or web work, they are underpowered with the 16MB Mobile Radeon. Apple really needs a high end workstation graphics chip in at least the high end PB model. People using these machines as mobile workstations aren't as concerened with battery usage as other users, and would value a higher powered graphics chip over an extra hour in battery time.
Apple needs to outfit the high end Powerbook with a nVidia Quadro2Go chip. Dell's Inspirion features this same chip, and it makes a world of difference when doing 3D, and of course, playing demanding games. I know several people in the market for a laptop drooling over the stylings of the PBG4 and OS X, but unable to get their work done on these machines due to the graphics chip.
I really hope that Apple waits a little while longer to get this right...