The XNU-Development team has wasted no time in attempting to bring an up-to-date kernel to non vanilla 10.5.5 users.

Apple has been quick in releasing the 10.5.5 kernel sources, and XNU-dev has been quick in porting it. The 9.5 kernel has been ported and internal testing is going on. The next beta for Voodoo will be based on 9.5 (currently beta 1 is 9.4 based).

Download
Currently an alpha test is in progress. If you are interested in helping, please see the Hardware page for information, and then download the Alpha 9 version of the 9.5 kernel from this page.

Testing Information
Please report all bugs on the Issues page. Also read this post to know how to get cpu id log, and attach it to your bug report. It helps a lot in finding out the problem!

If you cannot boot at all, or the timing is slow, or if it takes a long time to show the GUI (or blue screen), you should try the following options:

AMD specific: -amd -emulateintel (should no longer be needed after alpha8)
You could also give -force64 a try if you want to test 64bit support on AMD - this is very early stage so don't expect it to work!

Everyone: busratio=xx
where xx is your CPU clock multiplier (cpu frequency divided by fsb frequency). The FSB frequency is typically 100, 133, 166, 200, 333 or 400 Mhz.

Bootloader info
You need an EFI bootloader! Chameleon is highly recommended.
Pentium 4 users (and some other CPU users) need updated Chameleon -- dfe boot132 etc. might not work!
The updated Chameleon will be made available on their website when the final Voodoo kernel is released. Currently you must use the busratio bootflag as described above.

More information about XNU-Dev and the 9.5.0 kernel can be found over at the XNU-Dev site.