I'm thinking (searching in/out WP) for a 3-level access to the events calendar:
-user: who can comment, rate & report bugs on events
-editor: who can post an event (showing its name) and will be moderated by user ratings
-admin: as usual, gets over editor permissions, posts & comments
On top of the 'user features' I agree with the need of having recursive dates, several days events and different categories to be found within the calendar.
For all these 'date features' I believe it should be kept appart the 'posting date' from the 'event date', making extensive use of WP Custom fields, instead.
I may be implementing some event application for a client in a month time. I'd love to have it integrated within WP-2.0 and wouldn't mind to help if needed to deploy it.
Too many features? You asked for it ;-)
Thanx for any efforts done,