A-gps does work indoors tho, at least for me it does. I have noticed that if I use maps indoors, they will first show wrong place, but after a few seconds they scroll to my current position. It is not 100% accurate (it probably uses cell tower triangulation), but it works.

edit: you can see it's working when you get the dual green circle around your location in maps. One small opaque one and one large, transparent one.