When Google Maps v2 hit mobile devices, it used a clever trick of cell tower triangulation to guess where you were without GPS. Google’s new service, Latitude, lets you share your location with friends. That makes it a great enabler for ad-hoc get-togethers, based on proximity – “Hey, looks like you’re a few blocks away at the gym, want to grab a bite?” But it’s not just about social networking and locational advertising: Applications with location awareness could change the way we live.

The idea isn’t new-Loopt is already quite popular with the iPhone crowd (which for some reason can’t have Latitude just yet, despite their likelihood to use it). But this is Google: Latitude has more far-reaching implications.  The next killer apps will come from this convergence of location-based services, personal preferences, social networks and mobile devices.

Latitude currently appeals to the mobile-enabled teen and 20-something demographic – those with the most freedom to capitalize on spur-of-the moment gatherings. I can certainly see other interesting uses:

• Parents can play Big Brother, keeping tabs on our kids’ location when they’re out and about. Call it mobile “peace of mind.” Ethical issues abound.
• When traveling, either for business or pleasure, Latitude is a great way to keep track of people and navigate unfamiliar locales to meet up at cool places. While Dopplr, brightkite and Plazes (acquired by Nokia) can do this, users have to manually update their locations.

I like Latitude and can see using it occasionally, once the “new toy” effect wears off. I’d certainly expect it to have more lasting value than playing with iFart mobile. The really interesting implications are the improvement of relevance based on targeting, and context that apps can leverage–sometimes known as ads. While this will certainly make more money for Google, and might provide value for me under some circumstances, I’d take it a step further.

When mobile devices, like my phone, my portable GPS, my car (sure it’s a mobile device, in a sense) can all interact to improve my daily productivity, I’ll be a happy camper. I’m thinking of the day my Jawbone headset or Garmin Nuvi whispers to me -”You’re almost home, don’t forget to pick up your groceries today. You may want to stop at ‘name your local grocery store’, because a number of the items you usually buy are on sale. You can turn left at the next intersection…” or “You may want to fill up your gas tank now. You’ve got a ¼ tank left, but gas just dropped 10 cents to a one-month low. If you turn right on Monkland, I’ll take you to the nearest station.” Or maybe my phone says, “I notice you’re walking today. The next bus heading East comes in four minutes.”

Context is key.

Most of the puzzle pieces are there today and they can all “converse” (think BlueTooth)- they’re just waiting for some smart folks to make them fit together. Or if you’re Google, to release them all yourself.

Why should business users get almost all the productivity goodies? Just try taking someone’s BlackBerry away for a day. The consumer’s time has come. The gauntlet is down. It’s time for applications that deliver on the promise of expensive mobile devices, with impactful productivity that we can’t live without.

Despite almost 40,000 purchases on Christmas, somehow I don’t think apps like iFart mobile are gonna cut it – so to speak.