Although original plans were to baseline Habanero on JDK 5 and provide a JDK 1.4 compatible build (using JBoss Retro), the question of why we would support a JDK whose last major release was almost 4 years ago (see historical JDK releases) - and given how stable and commonly used JDK 5 is - does come up every now and again. This is why I've decided to put the question out to the community - which version of the JDK/JRE do you use JBoss Cache with?