I don't buy this whole "we use the lighting and audio sensors to detect where you are!" Lighting is so variable and there are no APIs to access said things (like exposure) on IOS devices in any efficient way anyway. I haven't done any true tests but when I fired up the app I got Color HQ which is a good 8 blocks away - not 100ft.
That being said, Bill Nguyen used to work with Steve Jobs so there's probably a fairly high likelihood that if there is secret API's and tighter integration with IOS than normally allowed.
Edit: someone should put a spectrum analyzer near the speakers of an iPhone that's running Color to see if they're doing any sonic stuff like Shopkick. I would but I don't have time at the moment...
Yeah my first thought was it was more of sound level and light level thing. So if you're somewhere dark and loud you're probably not in the same place as someone nearby who's somewhere quiet and light.
No, they (supposedly) use lighting and sound to see if two phones running Color at the same time in the same approximate location are likely actually in the same place.
For example, we could have the same GPS location while being on different floors of a building.
Built in GPS gets +/- 40 meters in an urban canyon like SF (i.e. worst case). I think for all intents and purposes GPS will get you 97% there for 3% of the effort as any of these other methods (which probably aren't implemented anyway).
In the real world (with signal problems, battery problems, and a skyhook database with inevitable errors) GPS is unfortunately not quite that good. I really wish it was though!
i'm basing my numbers based on my experience when I was at yelp - which always presumed a real GPS signal and not using any skyhook (or at least not only using skyhook).
That being said, Bill Nguyen used to work with Steve Jobs so there's probably a fairly high likelihood that if there is secret API's and tighter integration with IOS than normally allowed.
Edit: someone should put a spectrum analyzer near the speakers of an iPhone that's running Color to see if they're doing any sonic stuff like Shopkick. I would but I don't have time at the moment...