I wrote a REALLY big post here yesterday but when I pressed the "post" button I got tooo many user SQL error or something and after that Blitz site was unreachable... and I lost my post. Short version:
-I used cubelights in 3DMark03 wwII - there were not one single true light in there.
-Getting equivalent lighting with "true" lights would have required the use of 3-5 lights... too many!
-Cubelighting is fast, easy, and well supported (from GF1 onwards basically) and ONLY way IMO to make characters and other moving objects to blend in nicely if you are using pre-rendered (lightmapped) levels in your games.
-rendering cubemaps from the scene and using that is possible, but you really need to convolute the cubemap using for example free HDRShop... but raw cubemap might do also if you render it using very small size to get "blurring"
I asked cubemaps for Blitz because I wanted to use them for lighting, instead most examples used it for water reflections which is nice too, but not what I wanted. I still don't know if I can use cubemaps for lighting in Blitz.
More about the subject (and forget HDR and Spherical Harmonics, let's get cubemap lighting work first):
http://www.cbloom.com/3d/techdocs/cubemap_lighting.txt