We recently described  a lot  of  ways  augmented reality (AR) is going to appear on a mobile device near you soon. But now it's here: The first "real" iPhone AR  app has gone live in the iTunes App Store. It's specifically for Parisians. But it's arrived earlier than expected--weeks before Apple said it would be allowed.
And by early, we mean it's arrived in the App Store by stealth, snuck in as an added-feature in an update to an existing app--Metro Paris Subway. It's unofficial because technically Apple's is not opening the doors to full AR until it releases the new 3.1 code for the iPhone, which is widely expected in September. This code will add in a few more hooks to make AR apps work in a fully-integrated way with the iPhone's video functions...but it seems that Metro Paris's developers PresseLite have found a way to get it all working pretty well with the existing iPhone 3.0 code.
What they've done is create a way for you to find the nearest station on the Paris Metro simply by holding up your phone and looking through the camera at the view in front of you. You can also hold it flat and use it as a walking-guide compass--much as we've seen demonstrated in other AR navigation apps  before. This through-camera meta-tagged AR view of the world blends in data from the iPhone 3G S's compass and accelerometer sensors.
Check it out in the video below--which is also a good test of how well you remember your high school French lessons.
Cunningly, the guys have added in a few revenue-making extras too, like finding out where your nearest Starbucks or McDonald's is, as well as other shops and tourist attractions, and even taxi ranks--as long as the relevant point of interest is less than a kilometer from your current location. It's likely to be hugely helpful if you're visiting Paris and aren't sure of your way around...and it's available now for 99 cents. The list of points of interest will cost you extra, available through an in-app micropayment.
Of course we're not sure if Apple will let it remain in the App Store, as the company's officially told other AR developers that it won't approve full AR apps  until iPhone 3.1 officially arrives, and even the Metro app isn't perhaps as ideal as it could be--the metatags seem a little jittery at times, not necessarily panning with the rotating iPhone as well as they could. This is possibly a feature of the incomplete AR toolset available in iPhone 3.0. But at least it's a huge and tempting taster for the avalanche of AR apps that'll hit the store pretty soon.
If you're a Parisian, or a visiting tourist, grab it while you can: here --and let us know how well it works.