Newer Systems Technology and Other World Computing are now shipping processor upgrades for Apple G3 PowerBooks. The NuPowr G4 Pismo upgrades allow users the ability to boost processing speed from the G3 to the G4 at 500MHz. According to Newer Systems Technology:
Newer Systems Technology and Other World Computing today introduced the NuPowr G4 Pismo upgrade, the first-ever upgrade available for the Apple PowerBook G3 FireWire system, originally code-named "Pismo." The G4 Pismo upgrade allows owners of PowerBook G3 400MHz and 500MHz systems to upgrade to a G4/500MHz processor.
You can find more information about the NuPowr G4 Pismo upgrades at the Other World Computing Web site. The NuPowr G4 Pismo upgrade is available for US$299.00