The Mac OSX team, made up of people on Apple/PPC machines, has 1300 members, and has completed 188,604 units at the moment. The HardOCP team, made up of people on Intel/AMD boxes, has more than 5,000 members and has completed 1,802,804 units. Now, let's see - if I want to do some distributed computing, and have to choose between one platform or the other, which one should I target? Hmmmmm. That's a tough one. I guess I could choose the platform with the greater total computing power, but then again, the other one does have a fruit on the box...
For distributed/parallel computing, the speed of any one node is not an appropriate measure of performance - the only thing that really matters is aggregate performance. That's not what Apple wants anyone to take from this, but then again, they've always been better at marketing than just about anything else. ;)
By the reading, it appears that they still have a lot of slow G4s in the group. Given the PPC 970's vastly superior floating point performance (to both Intel and G4), likely 50% clock boost by the end of the year (with corresponding bus speed boost), and 10-20% speed increases due to the new compiler, the G5s should be really pumping up the OS X numbers through this year.