Lumped together as the “blogosphere,” these sites are sometimes seen as either the replacement for—or the enemy of—established news media. In fact, the blogosphere and older media have become increasingly symbiotic. They feed off each other’s information and commentary, and they fact-check each other. They share audiences, and they mimic each other through evolving digital journalistic innovation.

“The bottom line,” said Eric Newton, Knight’s vice president, “is that local news needs local support.”

A few blogs have grown into influential, for-profit digital news organizations. Upstairs in a loft newsroom in New York’s Chelsea neighborhood, Josh Marshall’s Talking Points Memo staff is combining traditional news reporting with an openly ideological agenda to create an influential and profitable national news Web site. TPM has grown from former print reporter Marshall’s one-man opinion blog into a full-fledged, advertising-supported digital news institution with a small group of paid reporters and editors in New York and Washington. In 2008, TPM won a George Polk Award for its investigation of the political firings of U.S. attorneys during the Bush administration.

Marshall described TPM as “narrating with reporting and aggregation”—including the involvement of “an audience with high interest and expertise. We have a consistent, iterative relationship with our audience—people telling us where to look,” Marshall said. “But all the information, stories, and sources are checked professionally by our journalists.”

Marshall also believes in “the discipline of the marketplace,” and has not taken foundation money or philanthropic donations. Only advertising and small contributions from readers support TPM’s still relatively small $600,000 annual budget. Its first outside investment is coming from a group led by Netscape founder Marc Andreesen to help Marshall expand his reporting staff and advertising sales.

TPM’s combination of news reporting, analysis, commentary, and reader participation is the model in varying forms for many blogs on the Internet. Some of the more widely read and trusted independent bloggers specialize in subjects they know and have informed opinions about, such as politics, the economy and business, legal affairs, the news media, education, health care, and family issues. Freelance financial journalist Michelle Leder, for example, turned her interest in the fine print of SEC filings into the closely watched Footnoted blog, which is supported by both her freelance income and expensive subscriptions for investors to an insider version of her blog.

They also are creating new ways to report news. In 2008, Kelly Golnoush Niknejad, a Columbia University journalism school graduate, launched a blog called Tehran Bureau, to which Iranian and other journalists contribute reporting from inside Iran and from the diaspora of Iranian exiles. In 2009, Tehran Bureau joined in a partnership with the public television program Frontline, which provides the blog with editorial and financial support and hosts its Web site. Frontline and Tehran Bureau also are collaborating on a documentary.

For most of the millions of its practitioners, blogging is still a hobby for which there is little or no remuneration, even if the blog is picked up or mentioned by news media or aggregation sites. Residents of Baltimore, for example, can currently choose among a variety of blogs about life there. Baltimore Crime posts contributions from readers about what they see happening in the streets. Investigative Voice, started by two journalists from the defunct Baltimore Examiner newspaper, and Bmore News, owned by a public relations firm, focus on the city’s African-American community. InsideCharmCity posts press releases from local businesses and government agencies. BlogBaltimore aggregates reader contributions with stories from local news media. The anonymous Baltimore Slumlord Watch blogger posts photos of abandoned and derelict buildings, identifies the property owners, names the city council members in whose districts the buildings are located, provides links to city and state agencies.

The most ambitious local blog there is Baltimore Brew, launched in 2009 by Fern Shen, a former reporter for The Baltimore Sun and The Washington Post, who has recruited freelancers, including other former Sun journalists, to contribute reporting about the city and its neighborhoods, mostly without pay for the moment. Shen, who runs the blog from her kitchen table with money from an initial angel investor, acknowledged taking advantage of buyouts and layoffs that took about 120 journalists out of the Sun’s newsroom in less than a year. “The folks that used to do things for a paycheck are now doing them for cheap or for free,” she said. “Somebody has to get these reporters back to work again.” She is hoping to take advantage of being named “best local blog” by the Baltimore City Paper to raise revenue from prospective advertisers and eventually create a paying business for herself and her contributors.

Leonard Downie Jr. and Michael Schudson are the authors of "The Reconstruction of American Journalism." Leonard Downie Jr. is vice president at large and former executive editor of The Washington Post and Weil Family Professor of Journalism at Arizona State University's Walter Cronkite School of Journalism and Mass Communication. Michael Schudson is a professor of communication at Columbia University's Graduate School of Journalism.