I have an old powerpc iBook G4. Upgraded to Karmic today and all is well aside from the shutdown and reboot freeze. This appears to be a widespread problem for both pc and ppc users from searching for a solution today.
Last messages on the screen are:
init: usplash post-start process (1944) terminated with status 1
* Shutting down ALSA...
* Asking all remaining processes to terminate...
I had the same prob. on my PB aluminium 15". In my case It happened to be the b43 module (wifi). Problem solved upgrading to the new kernel (bugs.launchpad.com search for karmic ppc and go for the kernel patched). See https://bugs.launchpad.net/ubuntu/ka...ux/+bug/476154