No, Hot Corners do not have anything to do with the hot spots in your oven that prevent even baking. I consider a Hot Corner in Lion an integral part of my Mac’s desktop. By pointing your cursor towards one of the four corners of your desktop, you can activate a shortcut of your own choosing. Most people use it to turn their screensavers on, put their displays to sleep, or launch mission control.
At its essence it’s a time saver. You can quickly get a task done without going to the Dock, or opening up your Applications folder. It can also function as a security feature, especially in an office where you are surrounded by several people. A quick swipe can activate the screensaver and in doing so, password protect your computer. By doing it repetitively, it can be an automatic gesture, and can only help you secure your Mac.
To activate and customized your Hot Corners in OS X Lion, click on the System Preferences icon located in your Dock. Click Mission Control. Wait until the preference pane pops up and look for the Hot Corner button. It’s located on the bottom left of the pane. Click the button and it will take you to a window wherein you can assign a command or shortcut to each corner of your desktop.
Hot Corners in Lion are a nice invention from Apple.