CalDAV (RFC4791) is a calendaring extension to WebDAV that took a good while to become commonplace, and which I’ve been looking at since, oh, 2005 or so.

Recently there have been a number of interesting developments around it, and as such I’ve amassed a few resources that I’ve yet to list here completely.

Date Link Notes
Jan‘11 Radicale is a simple Python server that implements enough of the protocol to be surprisingly useful, and is developed over at Gitorious.
Zanshin is an asynchronous Python client library that seems to be at least on par with the official one for very simple tasks.