I think the patch from Tuesday(0206/07) night removed the 'learning' ability thing. I am sure it is something that will be detailed more fully once they finalize it. Before the patch, my group mates were learning my Fists of Ice ability, so it was not just critters.
Non-monks learning fists of ice from mobs was addressed in one of the recent patches. I think the best way to think about learned abilities is it gives you a chance to learn an ability for your class before your trainer has it available, or at the very least sometimes may save you a trip to your trainer.