I too would like to see some current benchmarks, but it would be a huge battle of finger pointing and complaining by **BOTH** sides.
I would like to see not only application benchmarks, but also library/API and algorithm benchmarks as well. Let's test encryption, compression/decompression, encoding, test the things that make us wait the most. I don't really care how fast MS Word can scroll, that's what search and pageup/pagedown are for. I don't care how fast Photoshop can do a script of 90 filters, because when I use Photoshop my images are only 5 Mpixel from my digital camera. And the filters I use in Photoshop on those pictures usually take less than a second to run anyway. The last time I really had to wait any real time for Photoshop was back when I had a 90 MHz Pentium. I can wait one second for photoshop, but I wish unzipping a huge file was faster. I wish encoding video was faster. Let's benchmarks and complain about the things that make us wait the most.
I think it would be cool to pit some Apple engineers against some AMD & Microsoft (or Linux) engineers against each other. "OK, write code that'll encode DiVX as fast as possible... use whatver compiler you want and optimize the code as much as you can!"
In fact, Apple should have close ties to Pixar, because Steve Jobs is the CEO of both companies. Pixar should, in theory, be able to heavily optimize Renderman to render really fast on the G5. Now most of the big render farms run Linux on Intel and AMD CPUs, so Pixar would have to keep it fast for PC too. But I think it would be a cool benchmark and challenge for Pixar and Apple... if such close ties for that kind of project isn't illegal or anything.
Apple's doing some neat things on the OS level to make video and audio work faster, I suppose to make their own apps run better. There's lots of info on the 10.4 Tiger website. But I really wish they would do something about graphics, OpenGL to be exact. Maybe they are, but they haven't said much about it. Another area that need work are the compilers. Apple promotes gcc, which is a nice free general purpose cross platform compiler, but it needs more optimizations for the G5. IBM, the company who designed and makes the Power5 and PowerPC G5 processors has their own wicked fast compilers designed mostly for scientific applications. But it would be nice if they and Apple would settle on just one compiler to make better, rather than support two.