Walter Winchell, a household name from the 1930s into the 1960s, was the source of Heinlein's created word. Winchell was primarily a gossip columnist, but he styled himself as a journalist. He used the sound of a telegraph key to open his radio bits, giving a hint of "breaking" and of "news" that was not really present.
As World War II loomed, Winchell veered into politics, taking a clear anti-Hitler stance, pointing out a danger that few Americans, at that time, were willing to face. After the war, however, his politics moved to the right, communism replacing fascism in his pantheon of evils.
By the time he died in the early 1970s, Winchell had been all but forgotten, reduced to handing out mimeographed sheets containing the columns he had once broadcast nationwide. Though he did recognize the dangers of Nazi Germany early, there really had been little substance to him--nothing, in fact, beyond a certain level of entertainment. He had a real skill with words, but was satisfied with the superficial, never using his talent to explore the deep and complex problems underlying the surfaces that, perhaps, he mistook for the depths.
We've plenty of winchells around now. Bill O'Reilly, perhaps, is the best known of the entertainers who masquerade as journalists, but there are plenty of others. Though there is no one on the left with anything like O'Reilly's complete disdain for the professionalism that is supposed to be part of journalism, some progressive winchell's do exist. Greg Palast, for example, subtitles his webpage "Journalism and Film," unabashedly connecting reporting and entertaining, next to a picture of himself in a fedora--reminiscent of Winchell, whose similar hat was something of a signature. Furthermore, the page is sprinkled with ads for Palast products and many of the stories read as Palast promotionals.
These two are certainly not alone anywhere along the political spectrum. Sometimes, people like them actually produce good journalism (Palast has)--still, what they are presenting is a schtick. But don't get me wrong: We need a few more Palasts on the left--we just shouldn't mistake them for journalists.
As journalism as a whole has veered more and more towards entertainment (nudged by desire for profits and notice that straight journalism rarely fulfills), it has become easier and easier for the entertainers masquerading as journalists to succeed. Even Stephen Colbert, who clearly doesn't want to fool people, actually has many on the far right believing he is one of them, though he "only plays one on TV."
If we could resurrect Heinlein's "winchell," perhaps Americans (having a word for them) could begin to recognize these people, no longer mistaking them for the real journalists they play.