This looks like a good simple way of doing the popular refocusing. Looking at the pictures I think they are doing much less processing than the similar google app: Instead of a true gaussian blur in the other objects I think they just align all of the pictures so that the spot you pick is not blurry, and then add the frames together with the appropriate offset. This gives the out of focus areas more of a multiple picture look than a natural blur. Not quite a synthetic aperture, but not too bad either for $.99 and I imagine most people will not notice the difference.
One of the developers here, and thanks for the feedback -- that's a pretty good guess at what we were going for. It looks like this dropped off the new page pretty quickly but thanks for taking a look!