Geolocation isn't really anything new. In a lot of cases we've come to expect it. Most smartphones sold today have an on-board GPS receiver and it's considered a selling point for a handset to have one. Today's mobile mapping applications and Location Based Mobile Services make use of the location fix that GPS provides. We're used to our technology saying "you are here". Without this there'd be no Ovi Maps, no Google Maps, no Foursquare and no Facebook Places.

Long before we put up a network of over 20 satellites a less accurate version of geolocation was available. Pretty much anything that puts out a signal in the radio spectrum can be used to triangulate your position, if there's enough radio sources spead out over a wide area and if someone's done the leg work needed to geolocate you based on the position and strength of those radio sources. This can be done with mobile cell towers, with radio masts and more recently with the proliferation of wifi enabled access points, both in people's homes, in offices and in public areas.

Sometimes writing a talk and putting together an accompanying slide deck is an education in itself. You set out with a point you want to make and in researching the evidence to back up your assertions you find out that the point you originally wanted to make isn't actually correct. You could give up at this point, which is not to be recommended as you're already on the conference schedule, or you could accept that your reasoning was flawed in the first place and make your talk instead centre on why you were wrong.

Thus it was with the researching and background behind my talk at Where 2.0 in San Jose on Wednesday. Originally entitled as a declaration, it soon became obvious that "Ubiquitous location, the new frontier and hyperlocal nirvana" was missing a very significant question mark.

Whenever I talk about the privacy implications inherent in sharing your location with an app or service, I keep coming back to the idea that it's essential to be your own source of truth for your location. This is a slightly verbose way of saying that you need to be able to lie about your location or that you need to be able to say "no, I really am here" despite what other location contexts such as GPS, cell tower triangulation or public wifi MAC address triangulation may have to say on the matter.

Of course, it's never quite as straightforward as that and here's why. The two location based mobile services that are getting a lot of coverage at the moment are FourSquare and Gowalla.