Numerous government sites are using microformats as part of an open government strategy. This page serves to list examples throughout the world.
Alphabetically by country name, subsections similarly sorted by state/province/city name.
United States of America
The Colorado State Government site uses microformats and provides information about them and what tools to use with them:
The Maine.gov website has a home page microformats icon and link to more information on reusing information from the Maine.gov meeting calendar and agency list in your calendar application or address book, and listing a few tools to use with microformats:
Oklahoma's Official Website has a microformats link in their footer to a page where they describe what features of their website use microformats such as hCalendar, and what tools to install to make the most of microformats:
The Rhode Island State Government site uses microformats and provides information about how to use them:
The Vermont Official State Website describes their use of microformats and vcards: