I said a long time ago that Foursquare can make cities better. You have these augmented realities like Foursquare and Twitter and Facebook that provide these virtual nodes and instant feedback from anywhere, adding annotation around a physical places.

Twitter has been my life's work in many senses. It started with a fascination with cities and how they work, and what's going on in them right now.

IM is interesting because you look at your buddy list and, at a glance, see what your friends are listening to, what they're working on, what they're doing. The problem was that you were bound to the computer keyboard.

The strongest thing you can cultivate as an entrepreneur is to not rely on luck but cultivating an ability to recognize fortunate situations when they are occurring.

I love cities, and I love city governments in particular. But in politics it would have taken me 8 years from implementing a policy before I would get to see the feedback. With programming I could model the same policies and see the impact immediately. Technology is a far more efficient way to test.

Pick a movement, pick a revolution and join it.

I spend 90% of my time with people who don't report to me, which also allows for serendipity, since I'm walking around the office all the time. You don't have to schedule serendipity. It just happens.