I'd also only meet/play in a public card room. Really, though, what's the point? Poker is kind of a solitary pursuit, aside from the social aspect, and you'll be at a table with eight or nine other people anyway. No difference whether they're strangers you found beforehand or strangers you found when you arrived. I suppose it could be a good way to make friends with similar interests, if that's what you're looking for.
Meeting up with someone you already "know" from a message board is different, though. I met up with a "board friend" for poker last time I was in Las Vegas. There's also a group of us in my area from a (non-poker-related) message board that get together pretty regularly for drinks and camaraderie.
