I have a mostly-working Views Calendar module available at http://www.drupal.org/project/calendar. It's still a little buggy and the css needs tweaking but it is generally working. Create a view and select the Calendar display (instead of table or teaser). Add any date field to the view (CCK dates, event dates, node updated dates, whatever). Add three arguments, Calendar: Year, Calendar: Month, and Calendar: Day.
Navigate to the view where you will see a year of mini calendars. Click on a month name to see the month or a day name to see the day. Back and next navigation is provided for month and day views (not yet added to the year view). It comes with a default calendar that displays all nodes in a calendar by their last updated dates. If you like, select the Calendar view for the block, too to get a mini calendar in a block.
This was carved out of Event Views and includes the event calendar api and many of the event themes, all modifed to eliminate any reliance on the event module.
My plan is to get this working in 5.0 as soon as the preliminary bugs are worked out of it (because I need a way to do calendars in 5.0 without depending on the event module).