I'm pretty much behind the idea of leveling, actually. Coming up with a coherent, stepwise map of how to get from a layperson's ability level to mastery of a certain topic seems like it will have all sorts of benefits. I just think we can do a lot better than asking an authority on a given topic what they think everyone should know about it, to figure out which steps should go first or what should be considered a very basic level of competence - I think we'll end up optimizing for the wrong things, if we do it that way.