A post in Yahoo's blogs dated June 21st 2006 says We Now Support Microformats where thay state:

Yahoo! Local fully supports the hCalendar, hCard, and hReview microformats on almost all business listings, search results, events, and reviews.

I think that wide adoption by widely use portals was the next step for the success of microformats. In the near future we'll likely see more and more tools that make use of them. I would bet some money that Firefox extensions will come very quickl