Until recently, one of the biggest publishers of such microdata (in its earlier incarnation, microformats) was Upcoming.org, an events startup acquired by Yahoo

Until recently, one of the biggest publishers of such microdata (in its earlier incarnation, microformats) was Upcoming.org, an events startup acquired by Yahoo. Gordon Luk, the lead engineer, wrote an excellent post describing his frustrations with microformats: [...] my experience with being a microformat publisher has shown that things are exponentially more complex than they let on in the “sales pitch.” -- http://getluky.net/2009/01/08/a-warning-about-the-real-cost-of-microformats/ http://getluky.net/2009/01/08/a-warning-about-the-real-cost-... HTML5 Microdata seems slightly more rigorous and abstract, but still, commingling presentational HTML with an informal data API is just asking for trouble.