This piece in the Christian Science Monitor about news reporting from Iraq is a concise, definitive exposition of the concept of "news" as US culture has come to expect and define it. News has an "inherent limitation." "It can't give you all of reality. It necessarily focuses on a tiny piece of reality that is making the most noise at the moment."
During the invasion itself, what was making noise were our tanks and troops' forward progress (and of course Western reporters embedded therein were more able to witness same), so that such activities dominated the news, to the dismay of those who protested the invasion and blamed the news for being pro-Administration. Now, as the noise is being made by the guerillas' attacks on US troops (and coverage of same is available) the news has shifted to focus on that.
The effect is, of course, that now the Adminstration is claiming the news is biased against it.