Not sure of the Bluetooth but I have a factory fit CD multichanger and it is in the glovebox not the boot, very convienient but it does take up most of the glovebox which is fine for me as I only fill it with rubbish anyway!
You can definitely specify BlueTooth as an option on a new MultiJet. I am not sure whether it is possible to have the factory fit option retro fitted to an existing car. There are other, aftermarket, option available, such as the excellent Parrot systems.
I've paired it up with various phones, Nokia & Sony Ericsson. I have it trained so that you just say who you want to call and it calls them. Green button to call, red button to hang up. Minimum effort so you don't need to take your eyes off the road. Display shows who's calling. My microphone is installed up by the skydome control & the control unit is installed in the wee gap between the radio and speedo units.