To answer your question about who our competitor is, it's the same as it's always been (and always will be): the back button. Our job, as pg says, is to build something people want. We started by building checkins and attracted millions of users doing that, now we're moving on to building the best social city guide we possibly can as well as starting to explore interesting new ways for local merchants to communicate with their customers.
It's not about beating someone else. It's about building something useful enough that people will pay attention at all. That's what startups are really about.
if you want to talk about check-ins.. check-ins are commodity, i'm sure foursquare knows this. noone says "hmm.. what app to check in??? hmm what competitors to try?" they go "hmm.. what's interesting and fun way to show off and impress others while i'm here in this restaurant? facebook? foursquare? foodspotting?"
I believe this is primarily when you're starting out. You're trying to decide if there's a market at all and having competitors lends some credence to that.
Once you already have the traffic that FourSquare does, I don't think it matters anymore. One case where it might be different is if there were some paradigm shift where there were a whole bunch of similar companies for a long time and all of them had dropped out of a dying game while a single company was holding on -- but that's not going on here.
Go walls was in some ways a kind of straw an against Foursquare. You had someone to be "100:1" against. Now who is your competitor?
I would not call this inconsequential because it can also be interpreted as the non-viability of check-in sites as a distinct business.
I appreciate you engaging in the conversation but you haven't convinced me that this acquisition is in anyway irrellevant to Foursquare.