I have begun a learning objects page at http://docs.moodle.org/en/learning_objects . (I am working on a project related to this and could not find anything about learning objects in the official docs.)
I am not a learning objects expert, though, and invite anyone who is well-versed in this to add to and edit what I have posted. I am painfully aware that I have barely gotten the ball rolling.
I will keep reading and researching, of course, but in the meantime... Well, have at it!