Correct - Apple does not have a published support policy, the only committment they make is to support N-1 version of the OS. Right now that's 10.7 and 10.8. When 10.9 comes out this summer, 10.7 will drop. In the absense of a committment for support, the safe policy is to assume unsupported.
They do release Java updates, but I haven't seen a core 10.6.8 OS update (i.e. 10.6.9) in a long time.
