If there's anything bad about OS X Lion, it's that it provides many more opportunities for boring backdrops. By default, Mission Control uses the familiar grey linen background with a miniature of your desktop, and with the login screen, you just have the grey linen. Dashboard has that pebbled grey Lego-like background, while Launchpad uses a blurred version of your regular desktop image as a background. If that doesn't have you yawning, then you've probably had a few too many cans of Red Bull this morning. Now there's a shareware app, Lion Designer, from developer Moritz Wette, that makes your Lion-based Mac a bit more exciting to look at.
Install Lion Designer, and everything is customizable -- the background for Mission Control and Launchpad, the folder background for Launchpad, and the background for the login screen. If you do something wrong, there's a Reset button for going back to the defaults.
For your own images, Moritz suggests that you use PNG files that have the same or greater width and height as your monitor so that no tiling occurs. Lion Designer is shareware, so you have nothing to lose but your boredom. Download and install it now, and if you like what you see, be sure to send Moritz a donation to encourage development of future apps.