Of the three social media platforms studied, news-oriented blogs share the most similarities with the mainstream press. Bloggers almost always link to legacy outlets for their information, and politics, government and foreign events garnered the greatest traction.
There are, however, also some clear differences. While the biggest topic areas overlap, there was considerable divergence in the specific news events that garnered attention. In less than one third of the weeks did the blogosphere and traditional press share the same top story.
via journalism.org