Add the barcode scanner plugin to an iPhone project set to landscape mode. Run the scan function. A black bar, the width of the status bar, appears on the right-hand side of the screen.
See screenshot at http://yfrog.com/oewjpdp
Looking at this some more it appears to only be an issue when the app supports landscape and portrait mode - presumably its the viewcontroller not dealing with the app rotating that's causing the issue. There is a note in the code that rotating isn't working so I suppose the workaround is to ensure your app supports one orientation only.