I think this is (nearly) cool..
On your calendar, you can click "browse calendars online" which takes you the marvellous resource that is Office Online. Here you can select a calendar you might find useful and download it. This adds the calendar to your calendar list and if you select along with your own calendar, you can now overlay one on top of the other in the same way you can with another person's calendar.
What is NOT cool is the really rubbish one they have posted for the World Cup which would be really useful except that a) its in German b) its got a recurring appointment advertising some german motoroil website??? who checks these things??
On the other hand, using the "famous birthdays" calendar I can tell you that today is Gerry Kasparov's (sic) birthday - I assume they mean Garry??
So its nearly cool.