The post is solid, but one of the things I like most in here are the signs of looking at where revenue came from (the comment about only 1% of revenue coming from the entry-level plan).

I'd love to hear more from Richard about how they tested the impacts of moving from the $5 to the free plan.

And yes, it's definitely a solid strategy to delay revenue for users. I'm sure someone will argue this is Web 1.0-bubbly thinking. But, provided you're doing it in the way that Richard suggests, it's not totally insane. Twitter might not have found a great business yet, but at least they've gotten past one of the big hurdles -- getting people to come to the party.