Monkeybread Software (http://www.monkeybreadsoftware.de/) has released Transparent Screensaver 2.3, an update to their screensaver utility for Mac OS X. The utility adds a variable transparency overlay screensaver to the list of screensavers in Preferences.
With the screensaver running at 50% the effect is one of dimming the desktop and all open windows; 0% is black; 100% is completely transparent. With the screen lock option engaged, the user can continue to view their iChat Buddy List, iTunes Library, or any open process or window, while waking their computer from screen saver mode is password protected. If the user wishes to remain logged in to their computer, but prevent others from using it, he can lock the screen.
Version 2.3 makes Transparent Screensaver Mac OS X 10.6 (“Snow Leopard”) compatible; it also works with Mac OS X 10.5 .
MBS Transparent Screensaver 2.3 for Mac OS X is currently available as shareware, which is free to test for 30 days. A license is available from MBS for US$15.