[jmandzik]

I think a large part of the strong finish is a feedback loop. As it gets closer to achieving the goal, the belief that this concept could take off strengthens, which leads to more signups.

That and the press blitz, of course.

[sdqali]

And celebrity users endorsing it would have helped as well. For example - Robert Scoble, Stephen Fry (https://twitter.com/stephenfry/status/234695539357257728) etc.