For a while, there was a graphics option in the Second Life client called "global illumination". With global illumination, objects are rendered not just based on direct light, but also reflected light. Raul Crimson has a blog entry that shows a scene with and without global illumination; it gives you an idea of the difference it makes. There's definitely overhead involved with it, but it makes SL graphics more real, or should I say verisimilitudinous?
Unfortunately, we no longer have that choice, at least for now. From JIRA entry SH-2965, "Global illumination didn't even work properly. It was unfinished, and Runitai decided it was best to just remove it with the OpenGL 3 upgrade."
That JIRA entry asks that global illumination again be made an option. I hope you'll consider voting for and watching it. Thanks.