Pasadena, Calif.—In a move that takes on Google’s AdSense program, Yahoo! Announced Wednesday that it is extending the Yahoo! Publisher Network in the U.S. to small- and medium-sized Web sites. Initially available in the U.S. through an invitation-only beta, the Yahoo! Publisher Network is a self-serve platform that enables small and midsize Web sites to automatically receive ads from Yahoo! that match content on their sites. The first advertising product Yahoo! will be offering through the beta is its Content Match contextual listings. Content Match enables publishers to place Yahoo!’s contextually relevant listings on their sites and receive a share of the revenue generated by them.