Add support to:
1. See event postings in the newsfeed/timeline. (eg. Joe created the event "My important meeting", Sally is attending the event "Joe's birthday party"
2. Allow users to browse a calendar of events and see the details.
3. Allow users to register for events.
4. All users to create events.
If these cannot all be completed at once, I would suggest that #1 be done first, then #2, etc. in separate releases