I used Yellow Dog Linux on my iBook (Dual USB) and it worked like a charm. Only reason I got rid of it was because I didn't use it enough to justify the space being occupied by another OS. Give it a whirl and see what you think. 🙂
With Solaris just having pulled/reinstatedsupport for Intel (those folks with 90% marketshare), I don't think there is a snowball's chance of seeing Solaris for Moto.