I work in a WHSmith myself and we've not had any. Is it possible this is just a trial launch in a small area? That sometimes happens with partworks, just to test the waters before a national launch...
That seems to be the case, I asked in Forbidden Planet in nottingham Tuesday and the guy hadn't heard about it (though he was very interested once I told him) he said it was probably being trialed in one area like you said.
This does explain why there haven't been ads on the telly at least! I did wonder if I was going mad for a while.