Having just acquired an i-Phone, I've been able to take advantage of podcasts, using my train journey from Milton Keynes to London to listen to some background material on Parliament.
The BBC's "Today in Parliament" is available to transfer from itunes to the iphone before I leave my home. It is available as a podcast on iTunes or directly on the BBC's website. The Parliamentary website also has a podcast series to subscribe to - this morning I listened to programmes on Big Ben; Gladstone; The Budget & Biofuels - and as I type this I am finishing off listening to a half-hour podcast on robotics. Again free subscription is available through iTunes - or directly here.