Husband charged in disappearance of Laci Peterson and unborn child

What makes this case special? Laci Peterson's disappearance and her likely murder is tragic. Yet there were at least two other pregnant women in California within the last year who disappeared under suspicious circumstances. Is it that her husband is a suspect? Husbands are always suspects? Is it that she was young, beautiful, and with child?
The reason I ask this question is that I saw the story and reflexively I wanted to write about it here. Yet how is it relevant? I don't pretend to write for a news website. Here is the original story from MSNBC.com. Whoa! Scott Peterson was arrested as I was writing this post.
One has to wonder, who gets to decide which stories are newsworthy? Which murders are the grisliest, kidnappings the most heartrending, car accidents the most tragic, robberies the most shocking, foreign events the most important, etc.? Network executives might answer that the public decides indirectly by rewarding the most relevant news media with their ears and eyeballs. I don't think so. Public preference plays a role and is often blamed for the dumbing down of the news; but I don't think that is a fair answer. The news media filters the news to align with their own private agendas and biases. Journalists operate under the pretense of objectivity but most people would agree that "objectivity" is only a smoke screen to protect the journalist. I've come to prefer opinion journalism to straight news reporting since opinion and thus bias is already acknowledged. (at least I think it should be)
So to come full cicle in this blog post, why Laci Peterson? Why her particular tragedy? If her husband had been arrested two weeks earlier would anybody care, or would stories of death and destruction in Iraq been more important?
What is news?