The Joomla! Team has released Joomla! 1.7.0 on July 19, 2011. It was security release. Many fixes and improvements over the 1.6 version were implemented. Release notes are available on joomla.org for deeply tech folks.
The most notable for EVERY Joomla! user is the fact that you can update your Joomla! from 1.6 to 1.7 with one click right from inside the Joomla! administrator.