This is the first time I have ever seen a phone with a FM transmitter. I assume its able to stream music to a FM radio receiver.
Most Android phones that do this sort of thing do so using BlueTooth streaming.
My in-car media centre does this via BT but I can also see the advantages of a FM transmitter for standard car radio but know of none other that can do FM, but then again before reading this thread I would have said it cant be done.
Nokia have been putting fm transmitters for a long time in quite a lot of their smartphones - I'm currently using the C7 and use the transmitter in the car quite a lot. Really dont know about other makes, but it isn't a very common feature and I would love to see more manufacturers putting them in. I can't find any androids that have it, dont know if Nokia have plans to put it in a windowsphone. The N8/C7 era nokia phones are very good in my opinion, but they are phasing out symbian OS so I can't really recommend it