Conservatives tend to complain about how stories are covered. I think that their real beef is a lack of conservative bias than any real liberal bias, but then again I'm biased in that assessment. :P
But I wanted to give a fairly likely scenario. Let's say the economy continues to improve before the elections. The media will report on this, both because it's their job and because good news sells just as well as bad news, and most Americans are desperate for any good economic news they can get.
However I can see conservatives saying the media is being liberal for reporting good economic news because it will benefit Obama. The problem there is they are looking at the result and ignoring the cause.
Are there liberals in the media? Of course there are. I think liberals are more strongly drawn to careers in journalism than conservatives. Does that reflect in their reporting? Sometimes it does, but I don't see the media as being some monolithic liberal entity hell bent on distorting what's going on in order to further their agenda.
In the case listed above it would be a case of accuracy but not fairness. Should the media attempt to curry favor among conservatives by also reporting something negative about Obama (or the economy), in an effort to bring about fairness?