I would argue that the SO userbase is already highly focused - on developers. Its not "general technology site", just "general developers" site. Its not as if t

I would argue that the SO userbase is already highly focused - on developers. Its not "general technology site", just "general developers" site. Its not as if that's an especially large and poorly defined group. With a much smaller subset of potential users I think you'll also find a much more "focused" group of advertisers, i.e. a smaller group of interested advertisers.