Timothy M. O'Brien at O'Reilly Radar – Google Announces Support for Microformats and RDFa:

"On Tuesday, Google introduced a feature called Rich Snippets which provides users with a convenient summary of a search result at a glance. They have been experimenting with microformats and RDFa, and are officially introducing the feature and allowing more sites to participate. While the Google announcement makes it clear that this technology is being phased in over time making no guarantee that your site's RDFa or microformats will be parsed, Google has given us a glimpse of the future of indexing."