Jess: You mean IBM developed it. Apple had nothing to do with the development of it, no matter what Apple's marketing department tells you. Apple's marketing department will tell you alsorts of other exciting bendings of the truth. Like MacOS X being the most advanced OS on the planet, the PowerMac G5 being the world's first 64bit personal computer, and it being the fastest personal computer in the world, that the XServe was the first dual-RISC CPUed 1U server, faster than light CPUs, etc...
Closer to home, Apple famously claimed that they produced the world's first 32bit personal computer. Of course, all the Acorn people laughed at them, and Acorn printed a full-page pisstake in the national press.
I played with a PowerMac G5 at Linux Expo this week. I can tell you that Opteron machines *certainly* feel a good deal faster (not to mention a good deal cheaper) and is much of a muchness against a twin 3.2GHz Xeon with HT. In fact, I'd imagine the Xeon would win for most raw number-crunching tasks, because compilers and such are more mature for it.
TTOTD: Never believe what Apple's marketing bumph says: it's almost always misleading.