Tantek (among others?) has launched a site to promote XHTML-based microformats as a microcontent solution building on existing standards.
(Boy, poking my head into Yahoo 360 sure gets me up to speed on industry buzz quickly. Then again, that’s more a function of the social network I brought with me and a bit of currentness – currency – working together).
Anyway, check out the microformats wiki to see the formats being discussed so far, currently including
Other formats, including hReview (I’ve been looking for a unified review data model for quite some time – so we can make a distributed “epinions”-type network out of the world’s blogs), are under discussion as draft specifications.