It must be NSHumanReadableCopyright. You can also localize it if necessary, but you must first define it in a plist.
Adding a useful suggestion if there is interest in any of the other keys:
NSLog(@"%s \n%@", __FUNCTION__, [[[NSBundle mainBundle] infoDictionary] allKeys]);
which gives this result:
2011-11-22 17:08:02.072 MyApp [1007:707] -[SplashScreenViewController viewWillAppear:] ( CFBundleSignature, DTSDKName, DTPlatformBuild, BuildMachineOSBuild, NSBundleInitialPath, NSHumanReadableCopyright, CFBundleExecutable, CFBundleIconFiles, LSRequiresIPhoneOS, CFBundleInfoPlistURL, NSMainNibFile, CFBundleShortVersionString, CFBundlePackageType, NSBundleResolvedPath, DTSDKBuild, CFBundleResourceSpecification, DTXcodeBuild, DTCompiler, CFBundleDisplayName, CFBundleDevelopmentRegion, UTExportedTypeDeclarations, DTPlatformName, CFBundleURLTypes, CFBundleName, CFBundleVersion, UTImportedTypeDeclarations, CFBundleDocumentTypes, DTPlatformVersion, CFBundleSupportedPlatforms, DTXcode, MinimumOSVersion, UISupportedInterfaceOrientations, CFBundleIdentifier, UIAppFonts, UIDeviceFamily, CFBundleExecutablePath, CFBundleInfoDictionaryVersion )