Microformats are the forefront technology jewels in the "semantic web". They are meant to be easy to implement and thus quick to "flower". Right now there is no major consumers of microformats because there aren't many major producers of microformats because there aren't many major consumers of microformats... Today I was directed to Ray Ozzie's Blog (he's the new Microsoft Chief Software Architect, assuming that office from Bill Gates) where not only has he proposed what appears to be the killer app for microformats and making microformats truly powerful, but he also had his concept development group at Microsoft build it and release it under a Creative Commons license.
Basically, and I'm not going to give this paraphrase much justice so go read his blog, the leap that Ray Ozzie made was the simple one that one of the key inventions of the GUI era was the Clipboard and that the key piece to interesting and useful convergence (via microformats) is smart, ubiquitous (like RSS is becoming) "web clipboard". The name of the idea is Live Clipboard (following the Live nomenclature of Microsoft, backed by Ray Ozzie). For more, please check out the examples at Ray Ozzie's blog and the cool modern feedicons-like icon at LiveClipboard.org. This could indeed be big...