I've been quite busy with the engine lately. The new stuff is:
Each reflective object has it's own cube enviroment map. I support multiple bounces by spreading out the cube map updates over a number of frames. This means there can be some subtle "popping" in the reflections. Acceptable for my application.
I now support 64 or 128 bit HDR rendering. Pretty standard stuff where I do tone mapping based on image luminance. Of course there is also a bloom filter (as if we're not tired of that one by now;))
One of the biggest drawbacks with deferred shading is the lack of support for multisample antialias (at least with DX9). The usual thing to do is to hack antialias by performing an edge detection filter and blurring the image only on the edges. It's a dirty hack but it works quite well.
Dynamic indirect illumination
This is a variant of this paper. In short, I partition the world into a uniform grid, and at each grid point I capture the incident radiance field. This is done by rendering a cube map and then projecting it to spherical harmonics coefficients. The coefficients are stored in a number of volume textures. When rendering the frame, SH cofficients representing the incident radiance at each pixel are fetched from the volume texture and used to approximate the incident diffuse lighting at each pixel.
Right now there are some problems with my implementation but I'll solve that soon ;)
At last, the mandotary screenshot: