Spaces is a gem of Leopard!

I installed Mac OS X 10.5 yesterday and enabled the new "Spaces" feature. I expected Spaces to be similar to the multiple desktops that have been available on the many Unix and Linux windowing managers for more than a decade.

Spaces is so much more than that. I set OS X to activate the Spaces menu with a press of my "mouse button 5", along side the mouse button 4 trigger for Exposé. Now with a quick squeeze of the side button on my Logitech mouse, my four workspaces are instantly displayed. I can then squeeze the Exposé button to reveal any hidden windows within the workspaces. A click on any of these miniaturized windows switches you. This makes application switching insanely fast.

I recommend everyone get a mouse with buttons on the side and give this a shot.

Any other features of Leopard that new users have been pleasantly surprised by?