They all understand RDFa and Google has said they do in the documents I've read.
EDIT: Reading further down on your first link, they say you don't have to change to microformats and all search engines will continue to support all formats.
In your link, Bing even says they have no preference. Not that anyone uses Bing.
EDIT2: But notice they say they are focusing on just one format for schema.org but you don't need schema.org to make RDFa work and RDFa works with Google/Yahoo/Bing. That has its own naming scheme that is also well documented and probably better documented with more categories. It's also a web standard while schema.org is not.