wow these ppl are trying to squeeze out the last remaining money one can get out of these DOF devices...
http://en.wikipedia.org/wiki/Depth-of-field_adapter
Same concept as the 35mm adapters that was popular 5 years ago for video cameras, before video capable DSLRs came to market.. I used to own one of these, albeit a bit more advanced with a vibrating ground glass to remove the grains of the glass. Essentially, this solution is the same as pointing the iphone to your DSLR's optical viewfinder and taking the image from that.
I see these ppl didn't even bother to invest in creating a photo app for the iphone that flips the image for you. This is indeed the epitome of a crude solution. The only thing they had to engineer was the adapter for the iphone. The ground glass tube that comes with it has already been developed by various people online and is a very simple DIY project. I guess the $250 asking price takes into account the volume (or lack of volume) they expect the product will sell.