The southpark guys seem to lean toward the libertarian view. They may not be strict libertarians or may not even know what libertarians stand for, but their shows seem to have a lot of lkibertarian themes. besides, any show that hates barbara striesand as much as they do can't be all that bad.
As for Michael Moore, they are coming out with a new movie (with Thunderbirds type puppets) that deals with the current war on terror. They specifically mentioned ripping michael moore a new asshole in the article i read. They said that if you watched the first half hour you'd think they were total liberals, and if you watched the last 60 minutes you'd think they were hard core republicans.
While south park has a lot of *filler* shows (the russel Crowe episode was a complete waste of time), a lot of the time theres actually a pretty good moral to the show. I liked the episode that explained what horseshit the Mormon religion was, but at the last moment gave the mormons props for thier strong family values.