Santaduck at Macologist Forum posted a huge number of benchmarks to test the performance of Apple's Intel-based Macs:
Apple Computer has this year begun in earnest the Herculean task of moving its retail line of personal computers from IBM’s PowerPC architecture to Intel. We at Macologist have taken this opportunity to step back and examine three of the new “Mactels”, the Intel Core Duo iMacs (1.83 and 2.0GHz) , and the MacBook Pro, and to examine these in light of a wide range of other computers, ranging from the iMac G4 to the QuadCore G5 PowerMac.
The timing for such tests has never been better, as universal binaries (UBs) for many applications and games have begun to be released by developers—of course without an Intel-specific build of an application, it will be running in the PPC emulation mode Rosetta. When possible we have obtained UBs for games and benchmarking tools, as well as forced Rosetta, modes to illustrate the performance penalty of emulation.