I am not aware of any such publications, but Apple is pretty good about continuing to support older products. My old Tiger (10.4) machines are still getting security updates periodically. Of course, that does not mean that they are going to release any further updates to Tiger itself or will guarantee that newer versions of other software (like iLife, iWork, etc) will continue to work with Tiger, and certainly no new machine will run any version of the system older than what it shipped with. I can't say when phone or in-store support might cease... I don't generally need Apple support much.