Mac OS X Lion included a completely redesigned Dashboard application that, by default, acts as a separate space (or "desktop," if you prefer) to the left of all of your other spaces (or desktops). Many OS X Lion users enjoyed this simple, but much needed refresh to Dashboard. However, there are some upgraders to the new OS from Apple that absolutely hate the new Dashboard and would like it to go back to the way it looked and acted in Mac OS X Snow Leopard (by flying in above all of your open windows).
Luckily, Apple included a very simple way to change the Dashboard back to the way it was in Snow Leopard, even if you're running OS X Lion. Here's how to do just that:
Step 1: Launch System Preferences (Applications>System Preferences or Apple menu>System Preferences)
Step 2: Find the preference pane that is titled "Mission Control"
Step 3: Uncheck the check box next to the option that reads "Show Dashboard as a space"
That's it! Now, if you hit the Dashboard icon on your keyboard or go to the Dashboard app, it will fly in above all of your windows, just like in Snow Leopard.