This is a pretty good NewsForge article on the subject of CalDAV:
http://software.newsforge.com/softwa...6.shtml?tid=74
In the article Cosmo seems the most relevant to Zimbra as they both are Java based and run on top of Tomcat (
http://wiki.osafoundation.org/bin/vi...ects/CosmoHome)
It would be great to see CalDAV support but it really requires the client-side implementations to mature before it becomes a pressing need. Personally I would rather see more emphasis placed on a licensed standalone Outlook Connector for the open-source edition and an iSync connector as these two pieces of functionality would satisfy the needs of a much higher proportion of Zimbra users.
