Nigel, I opted for a ChatterBox GMRS X1. It's self-contained, runs on it's own rechargeable battery and can be worn on your belt or clipped to the helmet. It accepts iPod (or equivalent), cellphone, and pillion headset along with providing bike-to-bike communication (it uses something in the U.S. called Family Radio Service (FRS) with a range of around 5 mi) - don't know if this is legal where you are). I like it because it doesn't take space on the bike and I can bring it only when I need it...my only regret is that it is FRS and not CB (Citizen's Band) - CB is more widely used on bikes here. They also offer rider-to-passenger models that don't use the RF broadcast technology but still offer cellular and iPod connections.
Wait until the end of this month and get the chatterbox XB1.
Bluetooth EVERYTHING, no cables!!
Once Chatterbox do it everyone will and life will be so much better. Just wait until your wife gets off with yer head strapped to her waist and you'll understand why I like the no cables thing.