[Brian]

CalDAV calendars aren't supported on 10.4 - since OmniFocus 1 needs to maintain compatibility with that version of the OS, they aren't supported in current versions.

This is one of the things on our to-do list, but I can't quote you a specific timeframe when they might be supported.

If this means that OmniFocus doesn't work for your purposes, you should contact our sales folks: we have a 30-day no-questions-asked refund policy. Sorry!