Firstly I want to say that I use active corners.   I know that a lot of people don’t like that but personally it works for me.   Occasionally the mouse goes into the corner when you don’t want it too.  I find that happens less to me now than when I first started using active corners.   However while working on Leopard today I had my four Spaces on screen and I went into the top right corner of my screen (which activates Expose) and to my amazement Expose was activated on all the spaces windows.   So through a combination of Spaces and Expose you can see every window you have open on the screen.    Once more Apple think of ways to make navigation around your workspace(s) easier.   Thumbs up guys.   Looking forward to discovering more features like this.