Folks, I believe to test agps you need to use the method acwp after a reboot. That takes the gps receiver out of the equation and relies on the supl server to derive cell based location.

Now, there are many flavours of agps (refer wikipedia) but I believe my n900 was getting cell location while the gps and the supl. server were doing things to get an accurate fix. That cell location has definitely disapeared for me.

Doing a cell loc. first also makes sense as cellphone gps do not store sat. almanacs as do handhelds. Providing that is the job of the supl server and to do that it needs to know broadly where you are. That info saves the need for a sky search for sats and is one of the speedups made by agps


One can also test without location-test-gui by disabling the gps under settings - location but keeping network location enabled. Again a reboot is needed to flush the cache.
Phew - long, sorry.