This is about the G4 mac mini (with powerpc processor), not about the x86 one. Ive decided I wanted to dualboot Debian Etch (4.0) and OSX Tiger (10.4) on my 2005 Mac Mini.
Read it here
The installation procedure went smooth and I got a working desktop environment without any special interventions. The dual boot setup was automatically taken care of, at boot you can choose l for linux and x for osx.