Where is the Holy Grail of Calendars?

There have been quite a few calendar applications created. Outlook is the most popular, Google Calendar is used by a lot of people.

Here’s what we need: a calendar that is publicly available to view by others (free/busy info) and a helper application that finds the first free time when all parties can meet.

Here’s an example of the mess:

Next week is a meeting of four parties. Two are on the same Exchange server and can see one another’s calendars. A third party is on a separate Exchange server. The fourth uses Outlook, but not Exchange. There is no way the meeting organizer can find out free time from all of the parties.

Some people say you can synch to one service, then another, and then your BlackBerry/Treo and I say this is a hassle.

Where’s a central calendar server that can synch with a calendar standard and help the meeting organizers find available time for multiple parties?