This was requested previously by another user for an earlier version... http://drupal.org/node/194123 but I think the message was that it would have to be re-submitted for v6.
Basis: There are many events that extend past midnight. If a party starts Saturday at 9:00 PM and goes to 1:00AM in the morning, you would rarely even consider Sunday.
So, I wonder if it is possible for an event that spans midnight to only appear in one date block in the calendar view. i.e. seeing the bloack span through sunday is slightly misleading to my users. Especially when an event runs from 8PM - 12:00... we create an entire entry based on 1 minute of time.