I wrote the beginning of a tutorial for Athena last weekend. I started on a similar piece for writing tests for Athena apps, but haven't gotten anywhere interesting yet. This latter will cover nit in some detail when it is finished, which might be this weekend (but don't hold your breath).
Also on the Athena front, I added a minor feature yesterday, client-side
notifyOnDisconnect, the purpose of which you can likely guess. The first thing Glyph and I did with it was add a default handler for that event which makes it extremely obvious to the user that the connection has gone away.
The logging/debug console is also a bit nicer now that it doesn't spew 100 copies of every message. ;) And if you haven't taken a look at the new admin REPL in Mantissa SVN, you probably should. This will likely work its way backwards into Nevow as a generic terminal-esque or text-editing widget of some sort.