According to Tantek Çelik, microformats are a way of thinking about data and design principles for formats that are adapted to current usage patterns and behaviors. It's a set of imple open data format standards that a diverse community of individuals and organizations are actively developing and implementing for more/better structured blogging and web microcontent publishing in general. ([1])
Microformats are not a whole new approach, a big attempt to solve all taxonomy problems or even a unified new language ...
See also: semantic XHTML and the heavy alternative, i.e. the semantic web.
According to the Microformats Wiki, the main principles are
Microformats use semantic XHTML, but not all uses of semantic XHTML are microformats. Microformats follow a specific process and are intended to provide a way for publishers worldwide to easily interoperably exchange (machine readable) simple bits of data.
In spring 2011, Google, Yahoo and Microsoft banded together to create schema.org. It provides “a collection of schemas, i.e., html tags, that webmasters can use to markup their pages in ways recognized by major search providers. Search engines including Bing, Google and Yahoo! rely on this markup to improve the display of search results, making it easier for people to find the right web pages.”, retrieved 15:37, 8 June 2011 (CEST).
This initiative seems to be a direct blow in the face of RDFa, a bit like HTML5 was imposed vs. XHMTL 2
Read Schema.org for more information.
Daniel K. Schneider likes this approach quite a lot. It answers both the need for some structure and organization that is lacking in current contents and applications and the need for maxium flexibilty and little cost that is typical for education as I (and most teachers) practise ...