Actually true radiosity doesn't work that way, an object will reflect a lighter light from it's base before the dark part of the shadow starts, the reason being it's the closet part of the object to the surface, therefore it would actually project it's color there first "over-shadowing" shadow, it's a natural trick of light. So Even Maya or Lw, Cinema etc can't make it right because it's a true phenom. There's an article on light study about this if I can dig it out I'll post the URL.

Do atleast one thing a day that scares the hell outta ya!!