After the Joomla 2012 Joomla World Conference, the release schedule has been updated, or slowed down more like it. Joomla 3.5 will not be released until early to mid 2014. So if you were holding out to upgrade from 1.5 to 3.5, might as well jump on to Joomla 2.5. Joomla 2.5 is a Long Term Release and will be supported until mid 2014. And don’t forget, there is still a dearth of extensions for 3.5. Consider 3.5 a developer’s sneak preview that is not ready for prime time. Joomla 2.5 is the current version of Joomla.