I apology for my bad English, so please forgive me in case of any mistake while writing this.
I believe some of us have noticed that the fan seems not working properly with 10.5.7.
Actually the fan doesn't spin at all.
The problem is due to the fact that the AppleACPIPlatform.kext doesn't contain anymore the AppleACPIThermal plugin.
So basically to solve this issue it is enough to add AppleACPIThermal back into the Plugins folder and then, as usual, delete kext cache and repair permissions.
A screenshot to clarify what I'm talking about, showing the contents of AppleACPIPlatform.kext Plugins folder...

NOTE: You may also remove (or backup) the AppleIntelCPUPowerManagement.kext and the AppleThermal.kext.
Both kexts are used only with real Mac a can create false state with temperature and fan.
This is my AppleACPIPlatform, already modifed and it is based on 10.5.7.
http://rapidshare.com/files/249089739/AppleACPIPlatform.kext.zip.html
http://www.mediafire.com/?ii0wdxzynw4 Alternative link by "4bc" (thnx dude)
Instruction:
- Download and uncompress my zip file
- Remove (or backup) the original \System\Library\Extensions\AppleACPIPlatform.kext
- Remove (or backup) \System\Library\Extensions\AppleThermal.kext
- Remove (or backup) \System\Library\Extensions\AppleIntelCPUPowerManagement.kext
- Use OSX86Tools (http://pcwizcomputer.com/osx86tools/) to progress with:
> Install my modified AppleACPIPlatform.kext
> Clear Extensions Cache
> Set Extensions permissions
> Reboot the box
You will notice almost immediately that the fan starts to finally spin again.
I'm massivelly testing this since 1 week now, and the fan and temperature are perfect.
Hope this helps.
Cheers.

