Mark Baker comments...
CalDAV is a red herring. We need calendar-specific operations in HTTP like we need a podcast-specific URI scheme.This bothered me a fair bit too. Say I want to use WebDAV for authoring schematics of electronic circuits. The CalDAV precendent suggests I would begin a SchemDAV committee.
Makes little sense to me. On the other hand to make calendars or schematics more interoperable I think we should begin agreeing on what the HTTP verbs should mean relative to calendar or schematic resources.
Ideally we would agree what POST means when I send you an event description to your calendar. And that's probably the easiest one. We probably need to do other kinds of resources for and about calendars (and schematics) for searching, comparing, and calculating.
Given the recent ballyhoo of microformats vs. XML -- aren't we still dancing around the verbs? We need to agree on how to handle the verbs to get anywhere deep.