TiPb loves answering your questions, but we also love sharing our answers with the community in hopes that more people will benefit, and even better answers will present themselves (hey, that’s why we have them forums!). Today’s question comes from Stupendoussteve on Twitter:

ever heard of iPhone finding you at a previous address, states away, where you've never even taken the phone (post restore)?

We have! And TiPb answers after the break!

The iPhone uses Location Services to determine where it is. Location Services uses three (3) distinct technologies, and different iPhones (and iPod touches) support different levels.

The most precise, supported only by the iPhone 3G, is aGPS. aGPS uses cell tower-based GPS crunching to give you a fairly tight indication of your current position.

Next is cell tower triangulation, supported by iPhone 3G and the original iPhone 2G. Google mapped all cell towers in the US (and other countries), recorded their GPS locations, and then tries to determine where you are if it doesn't have -- or can't get to -- an aGPS signal proper.

The last -- and the one causing your problem -- is WiFi router mapping. Skyhook got into a bunch of vans, drove around the US (and other countries), detected WiFi routers in homes and businesses, and recorded their unique IDs along with their GPS locations.

For iPod touches, and for iPhones that aren't getting good aGPS locks, Location Services uses WiFi mapping to find out where you are. The problem you're encountering is likely that Skyhook recorded the location of your WiFi router when you lived in another state, and now when your iPhone is finding it, it still thinks you're at that old address, across town, or across the country.

Skyhook may eventually drive around and re-map your WiFi router, or you can go to SkyhookWireless.com and manually re-locate your WiFi in their system -- though in our experience it can take a long time for them to update either way.

We already knew that Apple's next computer operating system, OS X 10.6 Snow Leopard (estimated for delivery mid-2009) was leveraging some of the amazing work done by the iPhone team, including the highly optimized QuickTime X. Now Apple Insider brings word that things like CoreLocation and more Multi-Touch might be making their way back to the big desktop brother as well:

CoreLocation will utilize a Mac's existing networking hardware to triangulate the system's location in a manner similar to the way the original iPhone was able to use the technology to emulate a true global positioning signal. [...] Snow Leopard will also gain access to a new set of Cocoa-based programing interfaces for leveraging the multi-touch features of the latest MacBooks and MacBook Pros within their applications.

The synergy between Apple's desktop and mobile OS X development really seems to not only be benefitting both platforms, and optimizing R&D's bottom-line, but bouncing off each other in iterative splendor. Hopefully iPhone OS 3.0 can take a little back as well -- I'm looking at you universal spotlight search!

The iPhone Map App, which leverages Google's mapping services, became location aware with 1.1.3, and GPS enabled with the iPhone 3G and 2.0.

Basically, it superimposes a blue circle around the area it believes you're located. More confident the belief, smaller the circle. GPS lock, and a blue dot shows up. Only problem? Sometimes there's not dot and Google's lack of confidence results in a pretty huge circle. Well, last week Google's blog announced some improvements:

With today's launch, your location estimate will be centered closer to your true location, and we have also improved the calculation of just how good our estimate is. When we originally launched the "blue circle" on Google Maps for mobile, the circle usually stayed the same size no matter if you were in downtown Manhattan or rural Iowa. Now, the next time you're using Google Maps in downtown Manhattan, expect to see a much smaller circle that's also far more accurate. Conversely, when you're in a lightly populated area like rural Iowa, expect to see a much larger circle which also happens to be centered closer to your true location.

The best news? No update required. Anything tapping the Google force for location -- including the iPhone, benefits automatically! Enjoy!

Thanks to CoreLocation in the iPhone SDK, Apps can make use of WiFi, Cell, and A-GPS (for the iPhone 3G) information to keep track of where you are. Your Twitter feed can be tagged with your current location, or can show you just those contacts in a certain vicinity. A movie app can automatically fetch show times for all the theaters in a certain radius. A to-do app can pop up location-based (rather than just time-based) alerts, reminding you to help your mom change a lightbulb next time you're there, or ping you when you pass the electronics store so you remember to pick up that cable you need.

Convenient? You bet. Powerful? A game changer. Invasive? Er... Could certainly be.

What if you don't always want whereabouts broadcast, if you don't want everyone to know (or potentially be able to find out) where you are, when you're out shopping, where that picture of your child was taken?

Read on to find out how apps ask for permission to use your location, how you can change your mind and make them ask you again, or how you can turn off location services completely.

Apple enforces a policy that requires apps to pop up a requester asking your permission several times before defaulting to location aware status. In my tests, every newly downloaded app will ask for permission until it's agreed to twice. So, if you say "Okay" twice in a row, it will stop asking and begin using your location. However -- and unfortunately -- the same doesn't hold true for "Don't Allow". Using Apple's Camera and App Store apps, I said "Don't Allow" ten times in a row and it kept asking. Then said "Okay", "Don't Allow", and "Okay" again, and on the second "Okay" it stopped asking.

While Apple should, of course, allow users to just as easily default to a non-location aware state through some combination of repeated denials over time, they have baked in a couple of options for the privacy and security minded of us.

To disable Location Services completely, tap Settings, tap General, and then slide the Location Services switch to the "off" position. (You can always turn them back on when/if you want to use them later.)

To force apps to ask your permission again before using your location, scroll to the bottom of the General Settings, tap Reset, then tap Reset Location Settings. Next time you fire up Camera, Maps, or Apps like Twitterrific, Showtime, etc. they'll ask you again if they can use your current location, and you can agree or decline on a per-App basis.

And voila: control restored!