SabreDAV 1.5 released with CardDAV support
So there it is, CardDAV. Unfortunately there are not yet a lot of clients who actually use it, and it mainly comes down to iOS and OS/X, but I've been asked about CardDAV a lot and suspect more people will become interested in this protocol (especially if more vendors start supporting it).
I tried my best to write good documentation for the new stuff, but it's always very time consuming, and not as good as I'd like If you have time and the will to write more, let me know!
Lastly, a big thank you to Nick Boutelier for creating the new SabreDAV logo!