A great thank you needs to go out Martin Winpress. First he is part of the team that has given PowerPC users another great Desktop Enviroment to choose from with MATE. Second he has produced a solid distro that has PowerPC support in Ubuntu-MATE.
15.04 was a horrible release for PowerPC under Ubuntu. The release came with a version of xorg that was broken under PowerPC. Many users in the Ubuntufoums were really worried about weather or not it would be fixed. Then the same bug hit Sid right after Jessie was released. Thankfully it was fixed in Debian and the fix made it in time for the 15.10 release of Ubuntu-MATE.
The install for users with the radeon r300 driver is the same as I documented here. Sound, wireless, video playback all worked. One issue I saw and this is because I was testing on my iBook G4 is when you play video with mpv the fans kick off after a minute. This does not happen on my PowerBook G4, but it has a slightly better video card and CPU.
There was an issue with powerd crashing when I plugged in my iPhone, but it looks like that issue has been resolved.
One of really great features that come with this version of Ubuntu-MATE is an app developed by Martin called MATE Welcome. This tool gives you access to documentation, access to the community pages, and allows you to install apps. You can find more info here.
Another tool is MATE Tweak. It allows to change your window manager without having to logout and back in. It also allows to change your DE layout to with a selection of options. If you like a traditional Windows feel then select the Redmond layout or for OS X choose Cupertino.
With 15.10 there is better iOS support. In 14.04 and even in Debian Jessie if you are running iOS 8 or later shotwell fails to import your videos and photos from your iPhone. This issue is now resolved in 15.10. I am running iOS 9 and can import my photos into shotwell on my iBook G4.
In conclusion I am really excited about Ubuntu-MATE and the option it gives PowerPC users for a modern, secure operating system. If 16.04 is a continuation of I am seeing then the next LTS version of Ubuntu-MATE will be a distro to recommend.
Screenshot with the Cupertino layout: