Just finally made it to install openSUSE 11 PPC with all bells and whistles on a Apple PowerBook G4 with 667 MHz. Not all bells and whistles indeed as I use Gnome and not KDE for performance reasons and as my personal preference. I want to share all of that, maybe it helps someone on some similar hardware.
I downloaded the DVD and plugged the ehternet cable in as i did not expect wlan to work flawless. a dhcp server was present in the network i expected network setup to be automated for the first.
First trouble I stumbled into was, that I was not able to setup partitions correctly as the bootloader would not have been installed on any partition so this would have left my PowerBook unbootable. After looking around here i found a how-to in here and following these steps PPC Partitioning - openSUSE did the trick. So I had a partitioned hard disk that also would accept a boot loader and installing went on. I decided for Gnome for several reasons and one of them was performance, but how do they say? No recommendations.
After rebooting the configuration went through only to leave me with a black screen. X-server was not working properly. Switching to a console (ctrl-alt-F1) and loggin in as root I found the video not working properly. Later researching it i found out my video card is not supported by the ATI driver. Changing my /etc/X11/xorg.config to the fbdev did the trick then. Yes sax2 will complain that this resolution will not work but I don’t care about this. Who changes the configuration of an old laptop anyhow? At the Section “Module” I added Load “dri” for general video acceleration hoping that this is correct 
The other important sections of my xorg.conf look like the following now. If someone finds a mistake please tell me.
Section "Monitor"
DisplaySize 321 214
HorizSync 30-70
Identifier "Monitor[0]"
ModelName "TITANIUM-1152X768"
VendorName "APPLE"
VertRefresh 50-75
UseModes "Modes[0]"
EndSection
Section "Modes"
Identifier "Modes[0]"
EndSection
Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1152x768"
EndSubSection
SubSection "Display"
Depth 16
Modes "1152x768"
EndSubSection
SubSection "Display"
Depth 24
Modes "1152x768"
EndSubSection
SubSection "Display"
Depth 8
Modes "1152x768"
EndSubSection
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
EndSection
Section "Device"
BoardName "Radeon LY"
BusID "0:16:0"
Driver "fbdev"
Identifier "Device[0]"
Option "XaaNoSolidFillRect"
VendorName "ATI"
EndSection
As the sound was very low only, I was using alsaconfig (like described here SDB:AudioTroubleshooting - openSUSE which worked fine.
The repos do not work perfectly well for the PPC version so I removed the videolan repo but added packman ftp://spike.fa.gau.hu/pub/pmppc110 but also the Gnome, OpenOfficeOrg and Mozilla repos from the list of community repos, not sure what sense it makes though
Finding out vlan client did not work, I installed MPlayer but that only works smooth with the SMPlayer frontend, playing most formats I used as long.
Then I started to configure WLAN, which gave me the trouble I always had to manually reconnect to the network when rebooting. Changing the global options of the network setting with YAST from NetworkManager to ifup worked perfectly. Adding the gnome-netstatus applet gives me a vague idea about the signal strength of my WLAN. Though I found out, everything below 50% signal means its not connecting. But as I work mostly sitting in my garden thats OK anyhow.
So that was the journey and now most of the things work fine. Closing the lid to let the laptop slumber works as well as the pulsating LED does then. But trying to set to hyphenation failed as long. Well I can live with that. Internet and email gives me a battery live of about 4-5 hours using Firefox and Thunderbird for reasons. For the look I prefer the simple but tasteless Glider theme 
but using the additionally downloaded 4DWM window frames which are cool as on my old Iris.
Hope that helps someone.