I'm sure it's possible. The previous forum messages at the following links may give you an idea what customizations would need to be done to accomplish such a thing:
Limit Access To Events
add color choice [for] display of event title
Different categories idea
Showing pending events in grid template
** and when approved, the proposed events become public so regular site visitors can see them. **
Of course, if you set the calendar options so user's events require administration approval before being posted, they won't appear on the calendar at all until approved.
Dan O.
[This message has been edited by DanO (edited March 16, 2004).]