Xlr8yourmac.com provides clarification on the hot-topic of DDR in the new PowerMacs:
I'm getting lots of mails on this but as you can clearly see from the Apple PowerMac G4 specs page - they note the system bus bandwidth at 1.3GB/sec - clearly indicating that is *not* a DDR system/CPU (frontside) bus. Just like the Xserve, the new G4s use a single data rate system/cpu bus and a DDR memory bus.
Railheaddesign also provides a detailed explanation of the DDR implementation on the new PowerMacs.
