Why can't the TSA make me a suit? They already have the measurements. I'm barely half joking here. Seems like this is one of those unsolved "solved problems".
http://scholar.google.com/scholar?q=physiological+effects+of...
My general sense: any health effects are likely to be weak at levels typically encountered, but I'm holding as plausible that thee may be some effects.
Less so these days, but still.
My understanding is that there's a possibility of creating induced current in the pacemaker. Which is to say, the non-ionizing radiation has an effect at a distance, albeit in a manufactured artifact, not (in this case) organic tissue.
That said, other risks for pacemakers include store anti-theft devices, most of which are also inductive coils so far as I understand.
Effects of radiation chart showing induced current effect.