Modern GPS chipsets actually work ok in a lot of buildings. Some of it is higher sensitivity, but a lot is that they get location opportunistically (when entering/exiting) and then remember location. A-GPS helps a lot too.
I believe what most people believe is the GPS chip working is actually the location service built into the software. Unless they are transmitting in a completely different band GPS is practically useless indoors. Now with location services and AGPS you'll get a lock while indoors but the GPS chip is probably not doing much at this point.
I've got a Nook tablet without the GPS feature and I'm able to get my location from the wifi connection. It's not as accurate as a true GPS lock but good enough to get me information on the shops around me.
