Two companies have recently been demonstrating a new type of mobile-phone headset they hope will challenge Bluetooth by supporting existing mobile phones and cordless home telephones.
So, not only can the headset automatically switch a call or song from your phone to the headset when you put it on, but even if it's paired it won't ring the headset unless it's actually on your ear.
The base is connected to the phone through a headset connector and, given its apparent size, seems more appropriate for use with a desktop cordless phone than with a mobile phone.