There's no mention how the live feature works but I'd guess it's tied into the location services thing you can opt into on Android.

I really hope this doesn't turn into yet another death sentence via crowd sourced data (similar to review ratings on Yelp) to bars/restaurants that aren't getting full, making people think they're not good because no one is going there. The phenomena of waiting an absurd amount of time in line in cities like SF is quite popular.