Related anecdote:

A guy writing an on-line anime-ish saga picked a name for his fictional company that produces "real" virtual realities in his fictional universe. It happens to be the same name I've been using for my real company doing VR work for 5-6 years, with actual clients and so on. RealityPrime is the name.

I thought it might be potentially confusing to a client doing a goggle search for me (i.e., they might give up on discovering that RealityPrime is fictional), so I wrote the guy, very politely, and the simple solution we found was to put a disclaimer and link on his site for any wayward googlers. That's all it took.

The only problem I see is that with trademark, I seem to have an obligation to confront any infringements so I don't tie my hands against a malicious person who might come along later. Maybe I could just give this guy an official letter saying he's "allowed" to use my trademark. That might do the trick.