@zephyroth / roisoft:

and what about this thing?

There is now final extension fix from #leopard @ irc.osx86.hu.

You can get it here.
Unpack it an place it to /System/Library/Extensions/IONetworkingFamily.kext/Contents/MasOS/
If you used my workaround please restore your backup of NetworkInterfaces.plist.

This fix will set IOBuiltin = true for all network devices.

and at the following link there are more information about this error, it may help you:

http://sneosx86.freeflux.net/blog/archive/2007/11/12/_cfgethostuuidstring-final-extension-fix.html

(including users feedback with more information)