I can't say too specifically, but the song title stuff is part of the RDS, or Radio Data System. As I understand it, and with some help from Wikipedia, the RDS overlays a bit of digital info over the analog FM signal, and can therefore convey a short bit of text, including information about the radio station itself and the track being broadcast. Some stations make greater or lesser use of it, and of course your radio has to do something with it for it to display on your screen. It is distinct from digital radio, which has only been around for a year or two now. I saw RDS radios, if I recall correctly, 10 years ago.
I find it hard to imagine your 2006 Bimmer doesn't have any RDS capabilities, but anything is possible. It's pretty standard even in most American cars. However, some of the BMW radios are pretty booty - I've owned '89, '96, and '07 BMWs and I'd say only the '07 has a decent system.