ActiveBuddy, the guys behind SmarterChild and others, have just released the BuddyScript SDK. It's a simple way of scripting responses to word patterns the user enters to make chat bots on the ActiveBuddy framework, including ways of hooking into datasources. Not immediately useful for independent developers, but have a look at the Guide in the BuddyScript documentation -- it's interesting to see a way of solving the Conversation User Interface definition and state control problem (even though it isn't necessarily the one I'd use).