Kind of funny to have this making front page while the "Don't be a free user" link (http://news.ycombinator.com/item?id=3320931) is the top story. What is the business model here?
The business model is that free is on a shared and limited infrastructure so our costs are low. We also limit the number and resources for free. We have found that we had some room to offer even more without cutting into our margins significantly which is what drives this decision.
Thanks for all your great questions!