Kyle Rosenbluth on making Begin free:
Ben and I both love developing Begin, and our sincere hope is to continue to make Begin great for all users. At $0.99 for entry, we wouldn't have been able to keep Begin alive. I hope you can understand why we made this decision.
This is in fact a really good idea for a business model (if of course the developer(s) doesn't need to make a living out of it).