CalDAV  and CardDAV  are client/server protocols designed to allow users to access and share calendar and contact data on a server. There are many CalDAV and CardDAV clients around, e.a. Thunderbird/Lightning and also free CalDAV and CardDAV servers like Baïkal.
With that project I want to create a client in PHP to be able to create and modify data in calendars and addressbooks from websites.
 http://en.wikipedia.org/wiki/CalDAV  http://en.wikipedia.org/wiki/CardDAV
This project is one of its kind!