This monthly publication from the American Mathematical Society covers mathematics news stories from the mainstream media. It also includes a section on books, plays, movies, and television shows that are math-related.
Research Blogging identifies and aggregates blog posts about serious peer-reviewed research. The posts are about real developments in science; they are not press releases or news reports. Bloggers who want their posts aggregated must register. RSS feeds are available for all topics or by individual subject.
Terence Tao is a full professor of mathematics at UCLA and a 2006 winner of the Fields Medal. What's New is his blog; it covers "updates on his research and expository papers, discussions of open problems, and other math-related topics."