Facebook Inc. is testing a new ad format that lets marketers pay to show updates to their Facebook pages—such as new posts or contests—in the mobile and online news feeds of consumers who have not Liked their pages. The news feed displays the actions of a consumer’s friends; the feed dominates the page a Facebook user sees when logging on to Facebook.

The new ad format will be displayed in a similar fashion to the Sponsored Stories that appear in the news feed. That is, the lone way they will stand out from other items is that the post will be labeled “Sponsored.” Facebook is testing a new offering that lets advertisers infiltrate the news feed regardless of whether a friend has interacted with those brands.  Previously, advertisers could only promote their pages to consumers who had not Liked their pages via marketplace ads, display ads on the right side of Facebook.com, and Sponsored Stories, an ad format that appears in the news feed.

Because it is adding more ads formats that run in consumers’ news feeds, Facebook says it is being careful to use moderation. “We have limits in place to ensure that people’s news feeds are not filled with advertising,” says a spokeswoman for the social network. “Because we are showing people a limited number of ads in their news feeds, we will try to show them the most relevant ads.”

Facebook says the ad unit is being tested and is not yet available for widespread use. “This is a small test and we’re constantly gathering feedback from people on how to improve our ad experience,” the spokeswoman says.

This now makes it 3 new mobile ad units Facebook has started testing this year. I’m curious to see how Facebook users will take this. What do you think?