To all the people automatically assuming that this is a result of facebook acquiring instagram, what if this actually
improves the user experience? What if instagram always wanted to integrate with facebook because they knew it was a better user experience and yet didn't because they knew facebook was instagram's #1 competitor? In that case the acquisition enables a positive.
I, for one, could not give a crap about foursquare and yet use facebook on a daily basis. I understand foursquare has its community of supporters but I don't think any objective person will argue that foursquare is on a solid trajectory. In that case, it'd make sense to go with a more established player.