I think that there is a direct relationship between gravity and electromagnetic force. Unfortunately I do not grasp electromagnetism enough to define my suspicions. Where I diverge from what I understand your hypothesis (of gravity) to be, is that I believe gravity is an expansive force. There is actually a great deal of material on this on the web (see bkparque, einsteins velcro), however I think contemplation of this reality tends to make people insane. (sorry Brian) In other words, if you try to follow the thread you will find an unordinate amount of Rants. Not very pleasant or informative.

Getting back to gravity, if gravity is an expansive force, there is no need for the ambiguous graviton, and it could not be part of an E.M. wave or death ray or any kind of wave. In fact, if you take this hypothesis to it's logical conclusion, GRAVITY IS A PROPERTY OF ALL MATTER IN THE KNOWN UNIVERSE. But then, you knew this. So why would you think that some species of matter had this property and (presumably) some did not?