EDIT: I'm not asking about RDF vocabularies that is Google able to extract, but about the vocabularies that are actually used for enriching search results (i.e., data mark-up with these vocabularies are shown).
In the future, it will mainly be schema.org and GoodRelations. As part of the GoodRelations patterns, Google also understands foaf:page and foaf:depiction.
As a legacy, Google has said to keep up support for hProduct/hListing and data-vocabulary.org elements.
For new markup of products and businesses, I recommend the following guideline:
schema.org basic markup plus additional GoodRelations properties for details in Microdata syntax, if - your page is in HTML5 OR - your have events data on the page.
GoodRelations in RDFa syntax, if - your page is valid XHTML OR - if you want to use Facebook OGP meta-data.
Thats interesting. They used to support vCard and the Geo Vocabulary (along with a few others). Looks like thats all going to get washed away with schema.org
Is there a list of RDF vocabularies which is Google/Yahoo!/Bing etc. able to extract? Do you know the homepage URL?