Maybe this might interest you : 2 years ago, Stephane Marty (who
created Virtualight) issued a POV-Ray patch whoch allowed users
to select amongst 8 samples distribution shemes for radiosity.
http://perso.wanadoo.fr/albedo/patchedpov.html
If you download and read the HTML docs, you will see samples
of the availiable distributions.
Fabien.