iCal and Mail already work well with Zimbra via CalDAV and IMAP/SMTP, and I doubt that Apple will remove those in Snow Leopard. In short I'm not sure why Zimbra should/would try to implement EWS. Instead, if you want to get rid of the iSync connector, wouldn't it make more sense to find a way to sync personal contacts using open, non-proprietary standards? Snow Leopard Server and Client will support CardDAV (
link). This seems like the best way to go; LDAP might be an option although it's probably best used only for the GAL.
There's an RFE for CardDAV support, you might consider voting for it if you've got a vote to spare:
Bug 22008 - WebDAV: Add support for CardDav
Assuming that Address Book under Snow Leopard will work with CardDAV, then if Zimbra provides CardDAV, we'll have:
- For Mail, GAL access via LDAP (already works AFAIK, although I'm not sure how well it's secured)
- For iCal, GAL access via WebDAV principal-property-search report (should work once 5.0.17 is released, see links above)
- Address Book sync via CardDAV
It's far from clear what else Apple will or can do with Exchange via EWS, compared to what Mail/iCal already do with Zimbra.
- Entourage for EWS beta allows setting Out of Office, but it doesn't handle server-based rules/filters.
- Entourage for EWS syncs Notes; not clear how Mail will do this with EWS as it currently stores Notes using IMAP. As such, Mail's Notes are already perfectly compatible with Zimbra although they appear in mail folders, not as part of Zimbra's Documents.
- Entourage for EWS syncs Tasks; Mail/iCal already do so with Zimbra but there are some rough edges, largely because of some quirks on Apple's implementation. See Bug 35316 - improve compatibility of Tasks with To Do's in iCal and Mail.app