MacUser UK is reporting that Apple is discontinuing the 667 MHz PowerMac G4 model. The 667 MHz model is currently listed as the "Fastest" PowerMac model for the Apple Store, just below, ironically, faster 733 MHz models. According to MacUser UK:
Availability of both the 667 and 733MHz processors had been severely constrained until late February, which meant that both high-end Mac models were initially only trickling out of Apple. But by early March, 733MHz processors were available in abundance, allowing Apple to introduce a additional configuration with CD-RW drive for £2,099. While dealers could get plenty of 733MHz systems throughout March, 667MHz were virtually non-existent. Apple resellers are still trying to fulfil existing orders, but are now telling customers wanting the 667MHz to instead consider the faster 733MHz system, which only costs £100 more.
iThe 667MHz G4 was never a compelling option for our customers,i said one UK reseller who asked not to be named. iThe 533MHz model sits nicely in the middle of the range, and thereis even the dual processor 533MHz machine, so the 667MHz Mac never really had a home.i
Apple may or may not have ceased production of the model, but it is currently available at the US Apple Store. However, the price difference for the 667 MHz model is only US$200 lower than the 733 MHz model that ships without the SuperDrive.
There is much more information that we did not include with our quote, so definitely check out the MacUser UK story.