The upcoming openSUSE release (version 13.1) will be the next Evergreen release according to the openSUSE community manager Jos Poortvliet. Evergreen releases get security updates and important bug fixes beyond the regular 18 months support cycle. These releases are supported for at least 3 years.
The Evergreen support makes 13.1 a desired release for those who don’t want to upgrade every six months and would prefer a system supported for a bit longer.
Evergreen is an openSUSE initiative to increase the life span of openSUSE releases by offering security- and stability fixes after the normal 18 month lifespan of openSUSE releases. openSUSE 11.1 was the first Evergreen release and the current Evergreen releases are 11.2 and 11.4 which will be maintained till November 2013 (around 4 years of support) and July 2014 respectively.
So, if you are going to keep openSUSE on your box for a bit longer, 13.1 is the release you should be looking at.