As someone said above, it depends where you are. It also depends whether you mean a programme completely dedicated to folk music, or one where folk music is an integral part. For example, on BBC4 in the first few days of January 2007 they showed a programme called 'Viking Fire'. It was badly named, in that it didn't give much of clue what the programme was about, but it was actually a documentary about the Up-Helly-AA festival in the Shetlands. By its nature, that included a lot of Shetland folk music.