mac4lin ver 1.0_RC is released few days back. I think it is in much better shape now. As usual its well documented and this time installation is quite simple also(just one install script). I had a minor version problem with firefox theme which might have got fixed. Thunderbird theme is also nice. AWN theme is nicely integrated with Thunderbird, Pidgin by providing few notifier plug-ins.
If you want to install these themes manually then refer this documantation.
Here are few screenshots,
P.S.- I have not tried it on Ubuntu 8.10(intrepid), will update you soon.