The C64 Emulator by Manomio is now available for purchase in the iTunes App Store and sets you back mere €4. Alas they had to remove the BASIC interpreter to get approval, but the developer hopes to reintegrate it at a later date.
The app comes with the following games: Dragons Den, Le Mans, Jupiter Lander, Arctic Shipwreck und Jack Attack.
If you love one of these games and if you can live without the BASIC interpreter, you can get the C64 Emulator here.
More details on the C64 app are available at http://c64iphone.com!
Update: The app has been removed from App Store again. Obviously the BASIC interpreter was still part of the app which left to another ban after Apple found out about this! Bummer!