It also seems like the sort of thing android will eventually do for you, once it's developed & proven out. This isn't exactly old hat.

Unless you know.. patents.

The calculations look pretty complex. I think doing it on mobile devices would impact battery life, which is why Uber built a server farm instead of just adding it to their Android app.

Google has servers, so in a way Android could still 'do it for you'.

Don't they already do it? I thought the android location service queried google's wifi database to help figure out where you are.

Yeah, it does use wifi to help determine location. Doesn't use the technique described here yet though, obviously.