There is a general leftist media bias. Conservatives see it, Liberals deny it. I think Liberals deny it, not because they're lieng, rather, because they see their views as normal, and thus the media is reporting exactly what they think it should.
There is another note though, the media is anti-Israel. you just canot deny it. Even the papers is Israel are anti-Israel, but for different reasons. The ones in Israel are leftists (easily noticed by their views on religion) and most believe that peace with the Arabs is the answer. Unfortunately, that means that anytime an Arab kills someone, not to blame them. Outside of Israel, it's just plain bias.
In order to recognize the bias, a website called http://www.HonestReporting.com is dedicated to watching the media and reporting on it. It all started when the New York Times got a picture of an Israeli policeman saving a Jew from an Arab mob. The Jewish boy is full of blood. Unfortunately, the paper identified the Jewish victim of the Arab mob, as an Arab victim of the Israeli policeman.
Well, they gave out their "awards" now for dishonest reporting. With the background they provide, you can see the unbelieveable viciously anti-Israel bias of the British media, Reuters, and the general anti-Israel bias of most media outlets.