POV-Ray just recently made the move to 64-bit binaries, and thanks to the nifty SMPOV distributed rendering utility, we've been able to make it multithreaded, as well. SMPOV spins off any number of instances of the POV-Ray renderer, and it will bisect the scene in several different ways. For this scene, the best choice was to divide the screen up horizontally between the different threads, which provides a fairly even workload.
Notice the Task Manger graph above. I've included those to give some indication of how much an application occupies each CPU. In this case, SMPOV and POV-Ray show a near-perfect 100%, nailed-to-the-wall utilization across all four CPU cores in our dual Opteron 275 system.
Rendering is one of those cases where multithreading can bring huge performance increases. The dual Opteron 275 crushes everything else here, as one might expect, rendering the entire scene in 87 seconds. Note that the dual-core Opteron 175 slightly outperforms the pair of Opteron 248s, too.
The other big thing to notice here is how much faster the Prescott/Nocona core looks when additional POV-Ray threads take advantage of Hyper-Threading. The Xeon 3.4GHz shaves 50 seconds off of its render time with a second thread.