WordPress

WordPress is an open source blogging tool, that has been more broadly described as a "state-of-the-art publishing platform" and a content management system (content management systems).

Adding Microformats Support to WordPress

Become familiar with existing WordPress for microformats. Then:

There are themes available for WordPress that feature microformats support out of the box.

Sandbox theme or any Sandbox-based theme derivative will include hAtom, hCard, and xoxo.

Specific microformats can be integrated into the WordPress functionality through plugins.

See plugins tagged microformats on the official WordPress plugin repository for a sampling.
Blog Summary produces an hAtom-enabled list of recent entries via shortcode.

If you use the TinyMCE plugin, consider also installing the following:

TinyMCE hCard - adds a [1] icon in your tinyMCE toolbar that provides a form for creating an hCard contact.
TinyMCE hCalendar - adds a new [2] icon in your tinyMCE toolbar that provides a form for creating an hCalendar event.