Upgraded to Lion with an application in Snow Leopard called LaunchPad
Create a Time Machine backup of your current system, reinstall Lion, restore everything but applications from backup, then restore the other applications manually from Time Machine.



If you're feeling adventurous, and have good current backups, you could launch Terminal and enter the following exactly as shown:

sudo rm -rf /Applications/LaunchPad.app


Enter your password and the application should be removed.

Now you shouldn't have LaunchPad.app anymore. You could try to get LaunchPad from a friend, by installing a 10.7.2 combo updater, or by reinstalling Lion.