Would agree with what vRStu said, however when I had an MFD2, I used a Parrot CK3000 Evolution in the car. Mine was fitted with a special harness that allowed integration with the steering wheel controls, and therefore didn't require the little parrot control box fitting to the dash. If your car doesn't have a MFSW, then just use the little button.
I have to say it worked pretty well, so much so that now I have a RNS-510, it's still fitted and I can't really justify the £300 or so for ripping it out and replacing it with the VW/Skoda Bluetooth kit. At the end of the day it did and does what I wanted it to do. Mute the stereo, direct the sound through the drivers side front speaker etc.
If your Iphone is at least a 3GS (or better still a 4), then the built in voice dialling works really well on mine, so I don't really need the functionality of a built in address book on the RNS (which you would not have access to on the MFD2 anyway).
Better still, I picked up my kit new from the bay, for only £50, and fitted it in just over an hour. Works like a dream.
