Thanks for those thoughts, Mike. Perhaps I have a naively benign view of Apple, but if I were them I wouldn't worry about OpenOffice at all. Whether someone uses OpenOffice or iWork, that's one less person in danger of being captured by MS's strategy of bundling Entourage with Office. That person will probably turn either to Mail/iCal or to Thunderbird/Lightning, and as a result, will not view "Exchange" as the "standard" for mail and group scheduling. On this basis Apple ought to be OpenOffice-friendly.
However it doesn't seem this argument has prevailed (yet?) at Apple, since they don't support ODF in iWork as far as I know, although TextEdit will read/write .odt to some extent.
P.S. That's really good news about CardDAV! The bugzilla entry is equivocal about a target for implementation, but I see from
Zimbra Product Portal that CardDAV is slotted for 6.0.1.