Playing with fog and stained glass, here is the result, a bit tricky but it works.
I simply used a sphere around the camera with normals pointing inside and nothing else. The material for the sphere is specular with index = 1.0, subsurface scattering and fake shadows. Play with the scattering slider to find the best setting. Also I noticed that the best result is achieved using AO mode 4 with a value of 2-3, also refraction and reflection depth values should be around 4.
See the post and the sample from bepeg4d for more info : http://render.otoy.com/forum/viewtopic.php?f=33&t=28874&start=30
