[ugh]

There also seems to be some caching going on. The maps application in my iPod touch could track me accurately when walking around the city – with Wifi turned off. It seems to download the locations of all the Wifi routers in your area as soon as you have a internet connection, when you lose that connection it can still find out where you are (it needs only the MAC addresses).

Nice feature, pretty useless, though.

[gojomo]

I ran a test this morning, running the Google Maps application as I traveled to work. Wifi-only geolocation continued to accurately position me to the nearest intersection for about 3 city blocks after I left my home access point (and without connecting to any other access points for network access).

So it's got a cache of nearby access points it can use for positioning even without a network connection.

About 4 blocks away, it mistakenly placed me on a hillside 4 blocks in the opposite direction from my starting point -- but the local topography makes it very possible it caught a momentary signal from a faraway access point still in its cache.

From that point on, it provided no additional updates to my location -- even though I was following a 'directions' route previously called up, stepped through, and zoomed-on. From this I conclude: it precaches Wifi points near where you are when initially using location, but not along planned paths or all map areas viewed.

[trjordan]

The Wifi doesn't have to connect to know where you are. I'm pretty sure it's not doing anything fancy like caching -- it's just occasionally looking at available wireless routers and locating from their broadcast.

[smokey_the_bear]

Sometimes the location manager will also just report the billing address of your credit card if all else fails. And hey, a stopped clock is right twice a day.