These are projects related to the Trinity Desktop Environment. They have either been developed specifically for Trinity, or have been patched to work correctly with Trinity.
Trinity utilizes a patched version of libcaldav from libcaldav's Sourceforge site.
libcaldev is a client library that adds support for the CalDAV protocol (rfc4791). The object is to have a library which fully implements the protocol so that anybody with relative ease can add CalDAV support to there application. The latest patched sources and Debian binaries are available on the QuickBuild system: Go there now!
Libcarddav is a portable CardDAV client implementation originally developed for the Trinity PIM suite. It incorporates full list, get, add, modify, and delete functionality per the latest CardDAV standards. Build dependencies are minimal, requiring only libcurl. The latest sources and Debian binaries are available on the QuickBuild system: Go there now!