To the OP - wear a cap under your helmet, the brim will protect your glasses a little, and you want to stop rain from coming through the helmet vents. Use an anti-fog solution if fogging up is an issue. Otherwise, don't sweat it. Rain on eyeglasses isn't a big problem. A quick wipe with the finger of your glove should be enough of a "windshield wiper". If the rain is hard enough to interfere with your vision through eyeglasses, it is probably hard enough to interfere with the vision of those without glasses too. I ride in Portland with glasses.
I experienced some serious rain this evening - probably for the first time since i started riding. It didn't rain through the afternoon despite the weather forecast, so I took my bike out after dinner for a quick ride on the trail. As luck would have it, it started coming down pretty hard as soon as I got to the trail, so I ended up riding back home right away. It was a mere 20 minutes, but enough to show me what it's like to ride with the glasses on in the rain.
In a nutshell, you guys were right. It did bother me, but I was able to see fairly well through the raindrops on the lenses. I did have my rain jacket on, which sure helped. I think I'll need a pair of full-finger gloves. Mine is fingerless so I can't wipe the rain off my glasses!