I actually think CNN does a good job of putting out "objective" (not left or right leaning) news. The only show that had people touting the party line was "Crossfire" and that is off the air. I even respect their conservatives for being intellectually honest. For instance, Lou Dobbs immediately came out against the Social Security Reform and the bankrupt Budget proposal. For a rundown of their primetime pundits or anchors:
Judy Woodruff- probably liberal but doesn't really commentate.
Lou Dobbs-Conservative, but not a neocon and doesn't spit out the latest talking points
Wolf Blitzer- more straight news than commentary
Aaron Brown- Same as above, seems liberal though.
Larry King- idiot, but not political
Usually when issues are discussed they have most views represented. I do understand the sentiment that what most people (not those here) would consider extreme liberals aren't represented, but I think that's more indicative of the political atmosphere of the country than anything else. The majority of the people I know don't even know who Noam Chomsky, and probably wouldn't agree with most of what he says.
Is the viewpoint, i.e. extreme liberalism, so widespread that it should always be included in a news programs geared towards a national audience? I really don't know, if anyone has figures I'd like to see them.