It's not about media bias, although it was clear some on Fox were disappointed. (For example, one pundit said that Obama had won by a landslide -- another pointed out that the popular vote was actually fairly close, it's just the Electoral College that makes it seem like a landslide. A point I'm sure would not have been made if McCain had won.)
What was interesting is how conservative with a lower "c" before calling states for Obama or McCain. In fact, many websites were calling states, even the entire election well before 11pm when the networks decided they had enough hard evidence to call it.
Jacques Steinberg in the New York Times wrote an interesting article about "Burned Before, Networks Prove Reluctant to Name Next President Early" about the situation.
Personally, I've seen lots of tech reporters who were scarred and burned by the dot-com crash decide not to cover small companies for the same reason.