I, too, would LOVE to see even experimental drivers for nForce5 SATA chipsets. I've tried forcing the AppleNForce.kext to read my device and I was able to get it to read it, but it didn't last and it eventually locked up the installer. I also tried using the IOATAFamily.kext plugin, AppleVIAATA.kext, but it too, was only able to read the drives. This is better than nothing, though, and if there is anybody working on drivers for this chipset those might be a good place to start from =) Had I more knowledge and a way to easily test work, I would definitely try developing the driver myself, but alas, I've never owned a mac and I've never ran OSX86 on a machine of my own as this laptop is the first SSE2/3 machine I've ever had =)
My specs:
HP Pavilion dv6000us (BIOS says 6500, bought it under the number 6605, so I really dunno

)
Proc: AMD Turion X2 1.8GHz
Mem: 1GB
HDD: Western Digital 160GB SATA
Mobo (CPU-Z says): nForce 560
HDD on device: 10de:0550 which is apparently the nVidia MCP67 AHCI controller
DVD on device: 10de:0560
If any other info is needed to test or if I can be of any help testing drivers or whatnot I'd be more than happy to =)
Hope to get OSX on this thing eventually!