The missing killer calendar app

Surely I'm not the only person who could use a calendaring Web app that can host my desktop calendar (iCal) for sharing, allow me subscribe to it via my desktop app, and that can publish an RSS feed so I can get updates to the calendar (particularly for group calendars when someone other than me updates it). This killer calendar app would have to have:

1. a Web interface to manipulate the calendar from anywhere, by anyone who's authorized
2. WebDAV support for hosting my desktop calendar file
3. open-standard iCalendar publishing support
4. RSS publishing (ideally sliced and diced by user or date range)

Seems plain enough — and useful to tons of people: families, small businesses, etc. And yet I can't seem to find any such app. Is this what Backpack (more here) will be, in part?
    RSSCalendar is part way there, but it's missing the WebDAV and iCalendar publishing components. Big boys like Yahoo should have this built in to their calendars, but they don't. (Yahoo doesn't provide iCalendar publishing or RSS, and they opt for a third-party tool for calendar synching. iCalendar is the open format — third-party sync tools seem out of touch with Yahoo's push towards open standards, like RSS for MyYahoo.) Maybe they're working on it — or they're fixin' to buy someone else who already built what they need.
    What about you — do you find your calendaring tools lacking, too?