BBC iPlayer Downloader for Apple Mac, Linux, Windows, iPhone
Paul Battley has found a solution using Ruby script run as a command line application. This is a cross platform tool that will work on Mac OS X, Windows and Linux. There is a GUI interface as well, though the author recommends using the command line which works perfectly well within a Terminal window.
The downloader is able to handle bulk downloads through creating a list of programmes using the PID identifier in a text file.