It's like Foursquare/Facebook where you have to opt out of publicizing your entire life. I suppose advertisers (the FBI?) are drooling over the possibilities,

It's like Foursquare/Facebook where you have to opt out of publicizing your entire life. I suppose advertisers (the FBI?) are drooling over the possibilities, and that's probably what fuels the investment more than user excitement. Also, "everyone who was at the bar last night automatically sees the pictures (without any pesky 'publish' button or other form of 'opting in')" may be a more compelling user story than you give it credit for.