It doesn't really have much of a notable bias actually; in overall terms a slight tilt towards social permissiveness and an even slighter tilt to the right economically (which is more due to a larger tilt towards fiscal conservatism rather than towards right wing economic views in general). The impression of a genuine libertarian bias seems to come from the fact that the libertarians here (and there are actually less than you usually find in online political discussion things; well certainly a lot less than was common a few years ago) are just very, very vocal and like to be heard.
Bearing in mind the demographics of this forum in particular and the internet in general, there's nothing very significant to note IMO.
Very true Al. And in fact the 'bias' of the forum depends heavily on which sections you visit most, due to the composition of the posters who most frequent each of the sections. Someone might say "Constitution and Law" has a libertarian bias, while "Individual Politics" is fairly even if not liberally slanted. Some of the more election-oriented boards have a conservative lean to them. "The Atlas" has a whining bias, etc.