Greg,
Excellent question. I've been shooting shorebreak and other watershots and I've also had the problem of water drops on my port. If we're talking about the same thing, it comes down to technique. Most photographers, who shoot in Hawaii, spit on the port and rub it in a little bit at first before going into the water, and then once in, use the dip, point, shoot method. Normally, the chemicals and consistency of your spit are similar to what swimmers do for goggles- it helps to anti-fog the surface, and allow the port to bead water off the lense. However, normally for the first twenty minutes or so I've always had trouble with waterspots and drips down my port. I've not yet tried any artificial solutions to assist with the beading off process, but if you find something that works effectively I'd be interested in hearing your experiences.
-R. Yamada