The new version 3.6 has been released much later than anticipated; the release has been estimated for the end of April and has finally been released in early August. Therefore v3.5.x stayed the freshest available version for 234 days. How does this compare to the previous versions?
On average a WordPress version was replaced by a new one after 198 days. Outstanding is the version 2.0 which stayed the newest version for over one year (Dec 2005 - Jan 2007). Starting with version 2.1 WordPress development took a faster pace and the release of new versions took about four to six months. (Source: Wikipedia)