This looks nice. What is it like with ambient occlusion on?

I tend not to use ambient occlusion, global illumination, area shadows works fine for me. But the render took like 25 hours, glass behind glass behind glass etc, thats a lot of refractions, plus the reflection, my computer wasn't happy, so unless its a massive change I won't do another render.

I haven't had a chance to check this out, this might be of some help.
http://mvpny.com/R11GITutorial/R11GITutorial_Part1.html

and this is worth a good look
http://vimeo.com/11380324
look at his global illumination settings, this will definitely reduce your render time and still give good results.

Thanks Richie, I was actually meant to give some credit to you for this image since your one that won a short while back was my inspiration.

Love this, especially your step 15, really clever shapes you've got!