I am not so sure about that. MS has had significant contributions in research that is not directly relevant to Microsoft's current revenue streams - but I haven't heard if Gates was directly involved in any of them. Brin, on the other hand, appears to be spearheading that stream of research and development.

Brin and Page have compared themselves to gates and have mentioned they'd like to follow his example as far as philanthropy goes.

Except Brin is not paying for his past sins. Microsoft became a giant by doing a lot of very reprehensible things.