I don't really know anything about caustics. I'm using maya 4.5 and only have the sofware render. I have maya 7 PLE. It has caustics under the mental ray section, but i don't use the PLE. I don't like it. So i'm stuck with 4.5. i'm using a sinlge light source. No GI effects. Just wanted to see how the reflections and refractions looked. I wasn't worried about the shadow at the moment. Anyway, i'm gonna work on it some more when i get some free time. I'm busy with long hours at work and many days. When i get a free chance, I'll try to make it prettier.