Here is a good article for Blender render and lighting developers.-

http://www.osu.edu/researchnews/archive/shadow.htm

I was linked to this site from here-

http://www.flipcode.com/

I hope that these are good links for the Blender.org coders.

There's another thread on this topic posted about 2 hours earlier: http://www.blender.org/modules.php?op=modload&name=phpBB2&file=viewtopic&t=1688

I'll let the discussion continue there.

Cheers