Well I didn't meet someone on PerC (though there seem to be tons of awesome people here!), but I did meet my husband on another forum that I've been a member of for eight years. Our first anniversary is in three days.
Because of my own experience, and those of other people I know, I'd say it's more than possible to meet a romantic partner on PerC -- or any other online community. I love the way forums facilitate communication on topics that likely wouldn't come up when meeting someone in person, and that the nature of that communication is often much more open and sincere. I wouldn't change a single thing about how I met my husband... other than the fact that having a long-distance relationship for so long in the beginning really sucked. Totally worth it, though.

I've made a few very good friends on a couple forums as well, and hope to stay in touch with them for the rest of my life.