Mozilla's network "stumbler" client is installable from GitHub: https://github.com/dougt/MozStumbler/releases. The client code is at https://github.com/dougt/MozStumbler/ and the server code is at https://github.com/mozilla/ichnaea/.
I realise their mission is probably slightly different, but I at least feel it would be helpful to have all this kind of data in one place.
You mentioned further down you've reached out to other wifi mappers, but how about OSM?
There is at least one OpenStreetMap mobile app (Keypad Mapper on Android) which already allows submitting data to opencellid.org.
I got a ZTE Open to play around with, and was disappointed to find that it can't figure out where I am. Of course, I know it's a cheap phone and the OS is only in version 1.0. So if the location were a little inaccurate, or took a long time to come up, I would understand. But it literally never gets my location at all. (I live in NYC.)
Why do you think that would happen? And tying it back into this project, how soon do you think FxOS end-users will start seeing improvements from what you're doing?
Of course we are thinking about adding it to the play store, but there is no concrete timeline yet.