This app is designed to fix the signature mismatch problem that many users are experiencing when trying to update Superuser from the market. The problem comes from ROM developers using a version of Superuser that isn’t signed with the proper keys.
How this app works:
Included in the app is a copy of Superuser.apk that is signed with the proper key. The app copies the included version into /system/app which forces the system to reload the key to match the market version.
A rooted phone