ya i turned one of those pictured with many LEDS into my dome light, just had to cut away some of the housing, looks good.. www.autolumination sells them in all sorts of applications
I had been thinking about this the other day after following a bmw, i was going to talk to an EE friend of mine but decided i would rather not cut up the housings although it would look pretty sweet.. if you are willing to cut the housing though it wouldnt be too tough to make a board to fit there for someone who knows their electronics