DashLite is a process toggle for Dashboard, without the residual overhead when Dashboard is not in use.

Since Dashboard will not be running in the background, you may notice that launching it via DashLite is slightly slower.

DashLite will launch the Dashboard if it has not been launched yet. If a process name contains "DashboardClient", DashLite kills the Dock, which restarts. All Dashboard processes will be eliminated until next activation, thereby freeing system resources.

The best application of DashLite is in conjunction with a keystroke application launcher such as QuickSilver. You could easily keep using F12, or any other key combo you can configure, to launch Dashboard with Quicksilver or similar.