Beyond this project, there's a fork of QEMU that emulates a PowerMac G3 pretty well and is generally nicer than SheepShaver, but doesn't emulate a GPU properly and as such isn't suitable for some things (mainly games).
So for now I have a 500Mhz PowerBook G3 Pismo I pull out as needed, but it'd be really cool to have a full featured PPC Mac in a more compact form factor.