As you may know, the next OpenSUSE release will be OpenSUSE 13.1. According to this announcement from the official news site, OpenSUSE 13.1 will be an evergreen release.
The evergreen releases get many security improvements and bugfixes, after the 18 months of maintenance cycle, for at least three years. The first evergreen release was OpenSUSE 11.1. OpenSUSE 11.2 will be updated until November 2013, while OpenSUSE 11.4 will die in the July of 2014.
If you don’t want to change your OpenSUSE distro every six months, you should install OpenSUSE 13.1, in order to use it more than 2 years.