You can also buy an adapter for the Sena units to use a GMRS radio. That way you can talk to your Chatterbox brethren..
I LOVE my SMH10. Just paired it yesterday with my new GPS and am STILL in love with this communicator. Does everything I want it to, sounds great (I use the earbud base for the SMH10) and the batteries last all day and then some.
I totally forgot about that... I was looking at the Sena stuff before I picked up this new set of G9's, and that capability looked pretty nice.