Are you talking about this?
http://chaosspace.de/dev/launchpad-control-hide-apps-from-launchpad/
I'll take the chance too if so, at least it gives you some much needed control. I assume apple will provide something like this soon, which should have been there right from the start, and then some.
default: (says on their site at least)
Go to Finder and press Shift+Cmd+G. It should ask you which folder you want to access, type ~/Library/Application Support/Dock.
Delete your *.db file and rename the *.db.backup to *.db
That should make a full restore. You can also delete every *.db. The Launchpad will then make a fresh database.