I know, it's as much a study of techcrunch's sensationalism as anything else - the app has only been available for 6 weeks!

A very interesting case of the freemium model and in-app sales (up to $60) working very well, though.

I know what you mean about sustainability, but with the right publicity (it's all been word of mouth so far) and development it could have its 15 minutes in the limelight and that's really all you need when the ROI is as good as this. I was reading the comments on here by a seasoned app developer earlier today and thought this would be interesting to watch developing over time as a test case (whether they roll it out in other markets/languages/etc).

[Edit: thread I mention http://news.ycombinator.com/item?id=4389468]