Spaces
In short, you can be looking at a Mac with many virtual
"screens". Just because you don't see it, doesn't mean its
not there!
Virtual screen is something the Linux and UNIX user world has
ben accustomed to for quite some time. Now, Leopard is
offering the feature with Spaces. It is possible to have more
Desktops that monitors and simply switch between them by
choosing the virtual screen from the icon in the menu bar.
Looking at the menu bar, if you see a square with a
cross-hair and a number in the center, you are looking at the
Spaces icon and the screen number! Don't forget to check all
of the other screens to see what might be running. As with
anything of interest, consider using Grab to take screen
captures or window captures.