At our last meeting monan and I were discussing the Event and Date+Calendar Modules. I realized I didn't understand what Calendar was. Here is what I think now and what others are saying about this topic.
CCK and Views modules have taken the Drupal community by storm. The ability to rapidly create a CCK content type and Views views of that content type has given power to the user in ways we are still comprehending. The ability to export these new CCK content types and Views views has given the community the ability to replicate features across sites with out replicating all that clicking. Even as a programmer who has created modules before, I find the easy and logic of these modules irresistible.
Many CCK field types have immerged and the Date field type has brought with it the Calendar module. The combination of the Date field and the Calendar module in the presence on the CCK and Views modules could be substituted for the Event module.
There is much debate over the potential death of the Event module. But it seems to me that the battle is not so clearly won yet.
Some debate at -
http://groups.drupal.org/node/3598
http://drupal.org/node/114282
The Event module represents a more turn-key solution as it has no dependencies. Also there are several modules that have extended the functionality and provided integration with modules like Organic Groups. Date+Calendar requires a lot more configuration. Personally I don't really care about the ICal functions that Calendar provides. Also there seems to still be some flux in the Calendar module where the Event has been weathered a bit. In writing this, I have learned that Calendar is no longer dependent on CCK.
The argument about the dependencies is wayning because so many modules are now dependent on CCK and Views that I can't see a site being able to avoid it with out lots of custom modules.
There seems to work on an upgrade path from Event to Date+Calendar so you can delay your descion if you are invested in Events. I'm one of those invested folks and will stick with Event for now.
Setting up Calendar View - http://drupal.org/node/133341

Comments
calendar confusion
Maybe you can help me. I'm really confused about the calendar module and it's relationship to Views and CCK. I've got the calendar module working, and the calendar view set up. I've got a node type set up that I've created for events with the date field from the Date field type included with the CCK package. I've edited the calendar view to try to show events which include the date field, but I guess I'm missing something. All I have for the calendar page is a blank calendar. Am I supposed to be seeing related content within the calendar view, or do I have a misconception of how this is supposed to work?