StarPy is a Python + Twisted protocol that provides access to the Asterisk PBX's Manager Interface (AMI) and Fast Asterisk Gateway Interface (FastAGI). Together these allow you write both command-and-control interfaces (used, for example to generate new calls) and to customise user interactions from the dialplan. You can readily write applications that use the AMI and FastAGI protocol together with any of the already available Twisted protocols.
StarPy is primarily intended to allow Twisted developers to add Asterisk connectivity to their Twisted applications. It isn't really targeted at the normal AGI-writing populace, as it requires understanding Twisted's asynchronous programming model. That said, if you do know Twisted, it can readily be used to write stand-alone FastAGIs.
StarPy is Open Source and we are interested in contributions, bug reports and feedback.