There's always Persistence of Vision (
www.povray.org). It's an open source ray tracer and there are some Solaris ports out there. It's been around for a while, but it can compete with commercial renderers in many cases. Its output can be pretty impressive. Plus there's an MPI-based version (that's for Beowulf clusters).
My team, through an unbelievable stroke of good luck, has access to a 4 teraflop cluster from one of our sponsors so we're trying to figure out how to get from Maya to POVray.