Awesome! Volvos are fantastic cars.
The XC70 and XC90 have them on the side seats as well as the middle seat. What I've been told is that if the car has airbags (obviously being a Volvo they do have them lol) they are actually safer than the booster seat with sides because if the airbag hits the side of the booster the child in it gets banged against the booster but if the airbag hits the child it provides it with the protection that it is meant to.
The Dodge Journey has them too.
They are a great innovation.