From the Yahoo! Local blog (which is itself new), a massive announcement about Yahoo! support of microformats:
Starting today, we’re happy to announce Yahoo! Local fully supports the hCalendar, hCard, and hReview microformats on almost all business listings, search results, events, and reviews.
In sheer volume, I’m pretty sure this means Yahoo! Local has the largest implementation of microformats on the web. In a broader sense, I think Yahoo! continues to lead the way in opening things up in big-bang ways. Good job, Vince, Andy, Ronnie, and Yahoo! Local team.