If I read this correctly, it means that doc comments become actual values rather than just being discarded by the lexer/parser. Cool!
One of the tricks I like in Clojure is that docstrings are values in the metadata map for a var. That means you can use ordinary Clojure code to attach docs to a var, even outside the syntactic form that declares the var. When is this helpful? For a few libraries, it lets one provide very long docstrings (e.g., including examples) without unduly breaking up the source code.
That ability to manipulate the docs as values opens up some interesting abilities.