NEW YORK (MarketWatch) -- These days, the "M" in MSNBC might as well stand for Rachel Maddow.

Maddow, 35, has become such a cable-news fixture that it's a little hard to believe she has been hosting her show for only three months, since replacing Dan Abrams.

MSNBC has long needed a boost. It has frequently trailed rivals Fox News Channel and CNN in the ratings, and suffers from a rather spotty professional image at times as well. Sometimes, the network has seemed to be wildly undisciplined, where anchors in prime time are all but encouraged to throw any kind of broadcasting style or editorial concept against the wall and see if it sticks.

For years, MSNBC has been one of the most enigmatic stories in the media world -- and a problem child in the NBC News family. Its big brother, NBC News, has had the top-rated network news show in the breakfast and dinner hours for years. Even when Tom Brokaw retired from anchoring the evening-news program and Katie Couric bolted from co-anchoring "Today," both shows rolled on and didn't miss a beat.

Then there is MSNBC.com, which has helped pioneer uses of multimedia and graphics in more sophisticated ways than its peers. It has deservedly won awards for its prowess.

Recently, MSNBC had to retract a segment in which a mythical pundit "leaked" the "news" that Sarah Palin apparently didn't know that Africa was a continent. That even overshadowed a slip that Portfolio.com's Jeff Bercovici noted not long ago: "Chris Matthews just said that one of President Bush's biggest mistakes was his pledge to get 'Barack Obama' dead or alive." Read related item.

("Obviously, I was talking about Osama bin Laden, not the guy who just won the presidential election," Matthews added. I'm sure that guy, the President-elect himself, was pleased with the correction.)

To MSNBC executives, Maddow serves as a neat counterpoint to Keith Olbermann, who has also built a strong following. Olbermann is tough-talking, where Maddow is more subtle.

As the New York Times pointed out, MSNBC's ratings surged 158% during the final three months of the 2008 presidential campaign from the year-ago period. (Other news networks also enjoyed major increases during the end of the campaign coverage.)

MSNBC "grabbed special attention by topping CNN for the last month of the race, something it had never done before, and by occasionally topping Fox, the perennial leader, in the audience category to which news advertisers pay most attention: viewers between the ages of 25 and 54."

A pleasant alternative

One of the reasons for her popularity is that Maddow took the time to build a following and gradually let the public discover her.

Before taking on "The Rachel Maddow Show" on MSNBC, she appeared frequently on the network as well as on CNN TWX, . Maddow also gained a following from hosting a syndicated radio program on Air America (yes, she's a liberal; I guess the cat's out of the bag now).

Maddow is a pleasant alternative to the shouting and preening that passes for content on many of the cable-news shows. The General Electric GE, -1.29% network's newest star presents a nightly prime-time news program that stresses biting but civil discourse.

The audience has been noticing from the start, too. In the 25-to-54 year-old demographic, Maddow outperformed Larry King on CNN in 13 of her initial 25 nights on the air, allowing MSNBC to surpass CNN in her time slot for the first time.

What has been the key to Maddow's early success? Much has been made in the media about her lesbianism, intellectual prowess (a Rhodes Scholar, she has an Oxford Ph. D.) and penchant to dress down in a way that would make Joan Rivers blanch.

New York magazine's Jessica Pressler might have put it best, though. In a recent profile, she wrote of Maddow: "As one New York acolyte told me, 'She is more like one of my friends than anyone else on television.'" Read New York profile.

Is Maddow a star? You bet. I spotted this phenomenon first hand. A few Fridays ago, I had dinner in a Greenwich Village restaurant when word spread through the place that Maddow was seated a few tables away. At that moment, even the jaded New Yorkers in the vicinity craned their necks to get a glimpse of her. That is star quality at work.

The New York Times noted recently that Maddow "has made MSNBC competitive in that time slot for the first time in a decade. The channel at that hour has an average viewership of 1.7 million since she started on Sept. 8, compared with 800,000 before." Read New York Times story.

Still, Maddow has work to do in the 9 p.m. slot. Her show still trails Fox's "Hannity and Colmes" offering in the ratings.

Surprise star

Maddow's popularity comes as a surprise to veteran media observer Michael Wolff, a Vanity Fair columnist and the author of the forthcoming book on Rupert Murdoch, "The Man Who Owns the News." (Murdoch is the chairman of News Corp. NWS, -3.57% , which owns MarketWatch, the publisher of this column.)

"I am totally surprised that she has turned out to be a breakout star," Wolff told me on Friday. "She is an intelligent, down-to-earth person. (But) I never saw her as a kind of dramatic voice, and I know her from Air America....There was a kind of earnestness to the show, and to her, that made you think, here we are in the liberal ghetto. It turns out that the liberal ghetto turns out to be so large -- or that the conservatives are in a ghetto and the liberals have taken over."

I asked Wolff to analyze Maddow's success. "No surprises, no hysterics, no drama -- just the nice liberal, lesbian down the street," he said, tongue deeply in cheek

Tellingly, Wolff added, "Keith and Chris have much more flair, drama and pizzazz -- maybe that's the point. Good liberal earnestness is the thing now."

Maybe the point really is that cable news shows will now try to find Maddow-like commentators. Bill O'Reilly's breakout success at the Fox News Channel, a division of News Corp., as an in-your-face commentator has spawned imitators, to a degree, such as Olbermann and Comedy Central icon Stephen Colbert.

It seems to be Maddow's time now.

MEDIA WEB QUESTION OF THE DAY: What do you like or dislike about Rachel Maddow on TV or on the radio?