iPhones control interactive billboard in Stockholm to win McTreats

Ah, Sweden. The land of Akvavit, crayfish parties and billboards that respond to your iPhone.

You heard that right. McDonald's, not exactly a hotbed of Swedish cuisine but a popular place to eat nonetheless, has installed an interactive billboard in Stockholm. Enter a special URL, and you can play pong on the billboard with your iPhone. If you can survive for 30 seconds in the game, you get a digital coupon for some treats at Mickey D's.

What's brilliant is that you don't need to download an app to play the game - just enter picknplay.se into a browser, and a web app checks your location to verify that you're near the billboard. You knew there was a good reason to keep Location Services turned on all the time...

Another game on the same billboard has you snap a photo of a McTreat with a phone (not necessarily an iPhone) to get a free goodie at a local McDonald's.

It's an ingenious use of digital technology to engage people in interactive advertising. How about you, TUAW readers? Would you get pulled in by an interactive ad that takes advantage of a feature of your iOS device? Leave your answer in the comments below.