I spoke a little too soon about the difficulty of using Python for XMPP. While the pyxmpp package is completely devoid of documentation, I managed to USTL (verbing weirds language) my way to a prototype client that can connect to PubSub, get my subscriptions, and receive announcements. The design of pyxmpp is pretty easy to hook into, once you figure out what's what. And the entire kit and kaboodle is pure Python, which means any clients built on top of it should be cross platform.
Now back to fleshing out the remainder of a decent PubSub client. The major hurdle is adding support for subscription manipulation. After that, we'll be proceeding to some interesting hacks in watching the blogosphere.
Did I mention that a combination of PubSub and Gush is more addictive than crack?