Last revised June 2014
(Interactive - Full events link)
The most current release is Sakai 10, which was released on June, 2014.
Sakai generally maintains both the current major release and the prior one - which is now Sakai 2.9. However generally only critical bugs and security fixes are maintained in a previous release and in the maintenance release branch. It's generally recommended to upgrade to the newest version of Sakai shortly after it's released
Sakai 2.9 was released in 2013 and is currently in maintenance mode.
The major set of new tools and capabilities in 2.9 include:
For full details please see the TCC voting summary