Sun Labs has opensourced the Solaris PowerPC code base. From the announcement by John Crowell:
Sun Labs is pleased to announce the release to the OpenSolaris community of a long awaited update to the Solaris PowerPC code base. This release provides the community with a functional Solaris PowerPC development environment on selected target platforms. This is a modest, but important step toward reaching the goal of developing the Solaris PowerPC port project to the point where it includes the latest source tree, provides a shell or single user prompt on the target platform, and has enhanced debugging, ie: KMDB. Community members are encouraged to check out the latest information on the Solaris PowerPC port project page and/or join the discussion list.
You can find files and information for the project here.
The OpenSolaris PowerPC port will initially target the Genesi Open Desktop Workstation as well as Power Macintosh G4 and Mac mini systems from Apple Computer.