Google Search - Microformats Wiki

Google is one of several search-engines that index and support microformats.
Google.com supports rel-nofollow, hCard, hReview, hReview aggregate, hProduct (since 2009-05-12 for rich snippets), hCalendar (since 2010-01-22), and hRecipe (since 2010-04-13) - in main search. See also related blog post on hCalendar hRecipe support.
Rich Snippets is Google's term for the enhancement of search results ("snippets") with information from microformats from pages.
Google's documentation on Rich snippets - People support
hCard properties supported (bold = required)
Google's documentation on Rich snippets - Organizations support
hCard properties supported (bold = required)
Google's documentation on Rich snippets - Reviews support
hCalendar properties supported (bold = required)
Google's documentation on Rich snippets - Reviews support
hReview properties supported (bold = required)
hReview-aggregate additional properties supported in addition to the above (or additional requirements / subproperties)
Google's documentation on Rich snippets - Recipes support
hRecipe properties supported (bold = required)
Google's documentation on Rich snippets - Products support and Product properties: hProduct in particular.
hProduct properties supported (bold = required)
hListing (offers) properties supported (bold = required)
Related: Offer-aggregate properties supported (bold = required)
There is an obsolete claim of non-support:
"We do not currently support the hListing format for product rich snippets."
Real world examples have disproven this, e.g.:
Through additional user interfaces:
Google often shuts down sites or services, and some of those were implementations.
Google Social Graph API supported XFN (launched 2008 February). See "Google Social Graph API How are your sites connected?".