It's been pointed out that with today's computers and storage devices that it would be fairly trivial to record an entire day's worth of radio programming, but you'd still have to search through that entire day to find the song you were looking for and the broadcast of it has ostensibly been paid for.

And then you'd have a low quality copy of something that has had the levels turned way up past eleven with a DJ talking over the fade in and the fade out. But is it legal? You can time-shift legally, so there's at least an argument in there. If you were keeping it to archive you might have a problem.

Matthew