Nope, the other way around.
The task list can tell the calendar to display the due date of a task in the calendar view.
Like Yahoo's "My Time Guides": Lets you put holidays or club events or other things into your calendar.
But it'd be nice if it didn't require that you actually insert rows into the calendar tables. They can stay where they are, but calendar, when it displays the day/week/month/year/whatever view just includes those items.