In 2009, he published a book on the history of blogging, Say Everything.
In 2010 Rosenberg founded MediaBugs.org, a "service for reporting specific, correctable errors and problems in media coverage." In an interview, he explains, "We'll try to alert the journalists or news organization involved about your report and bring them into a conversation," which may get the error corrected. It is funded by the John S. and James L. Knight Foundation as part of their News Challenge. In September 2012, at the end of the funding period, he explained in a blog post that 'Much of the public sees media-outlet accuracy failures as "not our problem." The journalists are messing up, they believe, and it's the journalists' job to fix things.'