It's a matter of invitations versus context. Twitter is really good at providing context, like, I''m having coffee at Third Rail Coffee.' Foursquare is about invitations to places. In this respect Foursquare has started to replace Yelp for me.

The first complaint we hear from everyone is: 'Why would I want to join this stupid useless thing and know what my brother's eating for lunch?' But that really misses the point because Twitter is fundamentally recipient-controlled - you choose to listen and you choose to leave. But you also choose what to put down and what to share.

Short term satisfaction will never lead to something timeless.

I think that great programming is not all that dissimilar to great art. Once you start thinking in concepts of programming it makes you a better person...as does learning a foreign language, as does learning math, as does learning how to read.

TweetDeck is a very interesting client, because it presents a view that no other client in the world presents, which is this multicolumn, massive amounts of information in one pane. And people really, really enjoy that.

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.

You don't have to start from scratch to have a massive impact on the world.