Google Pack added a new quick install desktop access points (desktop shortcuts) to Docs, Calendar, and Gmail. These access points include placement in the start menu, shortcuts on the desktop, and a presence in add/remove programs. The applications open in Google Chrome, in the chromeless app view. If you click on the Gmail shortcut, you have to option to register Gmail as the default mail client. Google Chrome already includes Gears, so Gmail and Google work offline if you enable the option. You may have tried to customize this on your own but now it’s even easier.
More info: Google Pack