What are you actually looking to do? There are plenty of emulators that run on Linux, though I haven't checked which are still putting out PowerPC binaries. There are gaming centric distros but they tend to pop up once and not get major updates. Check distrowatch.com but I wouldn't hold my breath looking for one that still runs on PowerPC, they mainly focus on current gaming pc hardware. I would just get a known dependable distro that runs on PowerPC and install what you want from there. There wold be no real advantage in having a distro with an emulator focus except that the emulators would be pre installed.