HelpFormatter could be improved by adjusting automatically its width to the width of the terminal. The width of the terminal can be retrieved by the stty command on unix systems, on Windows it requires a native call. The JLine project on SourceForge already implements this logic.
I suggest to add a setAutoWidth(boolean) method in HelpFormatter that will try to get the terminal width. If it fails it'll fall back to the width provided by getWidth().