OSX 10.6.2 is out with no apparent changes to CardDAV support. I still see the following in the console (anonymised) when trying to add a CardDAV account:
Code:
10/11/2009 08:22:17 Address Book[232] [ABSPlugin-ERROR] 'Error Domain=NSURLErrorDomain Code=-1003 UserInfo=0x171dc5b0 "A server with the specified hostname could not be found." Underlying Error=(Error Domain=kCFErrorDomainCFNetwork Code=-1003 UserInfo=0x171dbed0 "A server with the specified hostname could not be found.")' during operation: Sending HTTP request: HTTP Request: PROPFIND https://user@domain.tld@my.zimbra.server:8843/↵ Headers: {↵ Depth = 0;↵}↵ Body: <?xml version="1.0" encoding="utf-8"?>↵<D:propfind xmlns:D="DAV:" xmlns:C="DAV:">↵<D:prop>↵<C:current-user-principal/>↵</D:prop>↵</D:propfind>↵↵ I've read the SL admin docs for Apple's CardDAV server app and port 8843 is used by Apple's CardDAV server implementation so one mismatch is caused by Zimbra not using the same. Adding :443 to the end of the server hostname box in the AB.app client appears to make it query the correct port on my server but the rest of the logged error message remains the same and account details aren't retrieved. Even if you press on and create the CardDAV account no amount of other fiddling appears to work, but them I'm simply making SWAG so I'm not overly surprised.
Again, it would be really nice to get some feedback from Zimbra Engineering on what their description of the problem is, what they know about Apple's plans *AND* what Apple bug numbers have been filed so that those in the community who are interested can express our support for Apple addressing them (pun intended) 
Christian