Apple has just released Mac OS X 10.4.2 to developers with some bug fixes and an improved widget download experience. This Mac OS X update will be released to the public real soon.
ThinkSecret also has some data from an Xbench benchmark that ran on Apple's Pentium 4 3.6GHz Power Mac system at Apple's Worldwide Developer Conference. However, keep in mind that this data does not reflect the native performance of these Intel-based 3.6GHz Mac systems. They only provide an indication of how PowerPC-compiled applications will run under Rosetta, an emulation technology to run PowerPC applications on x86 systems. Also keep in mind that there is still lots of time for fine-tuning.
Overall, the Intel Mac are scoring between 65 and 70 with Xbench, a far cry from the 200+ scores higher-end G5 systems reach. The CPU test is landing in the high teens compared with scores of 100 to 200 for G5 systems, but that appears to be primarily due to lackluster FPU scores. According to a recent Macworld story, Rosetta does not support AltiVec instructions, which substanties the results. The GCD Loop score for the Intel Mac, part of the CPU test, is a respectable 110, compared to dual-2.5GHz G5 Macs that score about 140.