High Fidelity [1] (Second Life v2) does this already. It's still early beta, but they've got the ability to map a user's face in real time with enough data-density to transmit emotion, and facial characteristics good enough to recognize a person by their avatar.
You are correct, that currently the same camera that does the facial analysis (macbook camera) precludes the VR headset - so you either get to see another in full VR, or you get to transmit your expression in HD. The device to do both is not yet here.
The founder of Second Life gave a live demonstration of this last night at the Silicon Valley Virtual Reality meetup. I didn't realize how important capturing these small facial gestures was until I saw it myself.
You are correct, that currently the same camera that does the facial analysis (macbook camera) precludes the VR headset - so you either get to see another in full VR, or you get to transmit your expression in HD. The device to do both is not yet here.
[1] http://highfidelity.io/