I remember reading a few years back that Alpha had marked the forums in some way such that it would disable search engines from picking them up. I remember because I tried to access the web.archives.com and it said the forums were marked specifically in such a way to not allow web crawlers to pick it up.
I believe, the term is "The Robots Exclusion Protocol", though I am not a web master so I wouldn't know.
Apparently this no longer is working, as google searches of penny-arcade.com are picking up forum topics. Just a heads up in case it's not supposed to be that way. Update your robots.txt file or something.