One of the charges leveled against Obama is that he doesn't have enough experience to be President. His response to that charge is interesting. He points out that the "mainstream media" doesn't cover his policy proposals, but covers burning issues like what sort of swimsuit he wears. According to his aides, he is very much against the kind of celebrity driven news coverage we have seen too much of in America. (You can click on the link in this entry's title to read more.)
There could also be another reason why he is criticizing the media. He has seen the GOP get away with it for years and has watched while it has been able to intimidate reporters with cries of "liberal bias." He has watched what Eric Alterman calls "working the refs". Just like a good coach will work the refs to get calls for his team or against the opposing team, Republicans have been working the refs for a generation or more to get favorable news coverage or critical news coverage for Democrats. They have successfully built a myth that news organizations are biased against them and that therefore people shouldn't believe what they read about Republicans unless it is favorable to them.
The attack that Obama is launching, that the media is too frivolous is actually much better than accusing the media of a "conservative bias." First of all, it is true. Second, the media would use charges of such a bias to tell the public that they are not biased. "See", they will say, "both sides claim we are biased, that is proof that we are not biased." Then, they will, with considerable self-satisfaction, go back to being just the way they have always been.
It is much harder, though, for the media to blow off the charge of being frivolous. In an age of celebrity driven journalism, when networks are cutting their news departments, when newspapers are forsaking investigative journalism of corporations and government to cover the shenanigans of Paris Hilton, it is hard to refute such a charge. Who knows, if all Democrats start doing this, it might just actually lead to better journalism.