VirtualScreens is a small app that resides in the System Status Bar (the rightmost part of the menu bar) of Mac OS X (Jaguar and Panther). It enables unilimited "virtual screens". A virtual screen is simply a user-defined set of active (visible) applications. When the user changes the virtual screen, the applications that were visible are hidden, and the hidden applications that belong to the new virtual screen are shown. In this way, you can reduce the cluttering on your screen and organize the running applications in the way that's most convenient to you.
What's new in VirtualScreens
Fixed a bug that prevented some apps from being hidden on changing screen under certain situations