python-jabberbot is a Jabber bot framework for Python that makes it easy to write simple Jabber bots. One can use these Jabber bots to provide information about running systems, to make Web sites interact with Jabber-enabled visitors, or notify the bot owner about updates or changes that are monitored with custom Python scripts.
Xmpppy is a Python library grown from the jabberpy project. Though this library has borrowed some code from jabberpy, it is a separate project with its own architecture and slightly different API. It is primarily intended to be used with the RFC-compliant jabber servers (like ejabberd), but it should work with all popular servers (including GTalk).
Twisted Words provides implementations of a handful of IM protocols, including IRC, MSNP8, OSCAR, TOC, and Jabber. It also comes with a multi-protocol server built around a few simple interfaces, the goal of which is to facilitate implementations of novel servers, clients, and bots. Out of the box, it comes with server that accepts connections over IRC and PB and seeks out installed third-party plugins to support other interfaces (for example, a Nevow LivePage-based Web interface).
antioch is a Web application for building scalable, interactive virtual worlds. Begun as a MOO-like system for building virtual worlds, the goal was to take the LambdaMOO approach to creating online worlds, and update it in hopes of attracting new players to an old idea. Like many MOO clones before it, antioch uses Python as its internal scripting language. This provides a powerful environment for game authors, while a flexible object model allows for creation of complex in-game objects.
Pynfo is a combination IRC info, search, and network relay bot. It supports basic fact definition (with persistence between runs) and searching of Google and Dict.org. In the network relay mode it "bridges" channels on different networks by passing messages between them. It also has a plugin interface, allowing users to easily define new commands.