JP from Japundit points out this Engadget post about Cardo Systems' new Scala Rider, a Bluetooth-based wireless headset for motorcycle helmets.
It can be attached to any helmet, unlike an integrated helmet-headset version that bike gear maker Momo Design announced last September:
Importantly, the photos in Cardo Systems' image gallery show the Scala Rider can be used with full-face helmets. I would have thought the bottom of the helmet would block the microphone, but apparently it doesn't. I wouldn't trade away face protection for the ability to chat on the phone.