NewsTrust.net, a not-for-profit that is moving into the news-rating turf staked out by sites like Digg, Reddit, and Newsvine, has landed a $450,000 grant from the MacArthur Foundation and plans to add a tool in 2008 that will let users label stories as having a left-wing or right-wing slant.

The two-year grant from the John D. and Catherine T. MacArthur Foundation will let NewsTrust expand its services, said founder and Executive Director Fabrice Florin.

“This will be the first place to break down stories by political viewpoint,” he said.

NewsTrust, based in a Mill Valley, California, was launched in November 2006 and remains in beta. The site gets “tens of thousands” of monthly unique visitors, far fewer than Digg, which had 6.3 million in October, according to comScore Media Metrix.

Scott Maier, an associate journalism professor at the University of Oregon, said news-rating web sites such as NewsTrust provide a vehicle for reader involvement not found in old-line media

“What I like about this is it provides a vehicle for reader feedback not to just the public, but in a broader sense,” he said. “One of the powers of the Internet is to share good stuff among ourselves.”

Still, he added, that some of the reviews should be taken with a “grain of salt” given that they came from only two or three readers.

Three-year-old Digg, backed by Greylock Partners and the Omidyar Network run by eBay founder Pierre Omidyar, has been the subject of recurring acquisition rumors involving potential suitors from Yahoo to News Corp. to The New York Times Company. Digg did not respond to a request for comment by deadline. Reddit was acquired last year by publisher Conde Nast and Newsvine was snapped up last month by MSNBC, the joint venture between General Electric’s NBC/Universal and Microsoft.

NewsTrust, meanwhile, has been bootstrapped by Mr. Florin, a former executive at Apple Computer and Macromedia, with some additional funding from angels like Craig Newmark, founder of craigslist.com.

Mr. Florin, who maintained that NewsTrust is not competing against the likes of Digg, said that the not-for-profit is run like a business and online advertising, memberships and licensing deals all are under consideration as revenue generators.

“I don’t think we’re a threat to Digg,” he said. “It’s useful to have popularity metrics.”

Unlike Digg, whose home page is heavily peppered with stories on technology from the blogosphere, the mix on NewsTrust is a more conventional mix of national, international and political news, including many stories from mainstream media outlets like The New York Times and The Washington Post. Reviewers are asked to evaluate stories based on a list of “core journalistic principles,” including fairness, sourcing, and context.

NewsTrust’s stable of advisors includes Dan Gillmor, former technology columnist for the San Jose Mercury News and founder of Bayosphere, a citizen journalism company that failed to momentum and was sold to rival Backfence.