Steve had better hope that he gets Leopard out at the same time as the new Intel-based Macs hit the market if these benchmarks are any indication...

"Individuals attending Apple's Worldwide Developer Conference have submitted Xbench benchmark results from Apple's Pentium 4-based Power Mac systems. The benchmarks do not reflect native performance of the 3.6GHz systems, however, but rather provide an indication of how PowerPC-compiled applications will run under Rosetta on Intel-based systems."