Google is launching a massive semantic search update. This update impacts of all searches. This is the new update to the Google algorithm this year. If your site relies on people, places, or reviews to generate traffic it is time to get serious about microformats.
support.google.com/webmasters/bin/answer.py?hl=en&answer=99170
support.google.com/webmasters/bin/topic.py?hl=en&topic=1088474&parent=21997&ctx=topic

Free Webmaster tool for this: www.google.com/webmasters/tools/richsnippets

Update 1) 30.05.2012

microformats.org news about microformats
schema.org collection of schemas
www.optimum7.com/internet-marketing/web-development/microdata-for-wordpress.html Example plugin microformats

Update 2) 30.05.2012

semanticweb.com about semantic web technology