We now have prototypes for both the iPhone 4 & 5. We tested them against the Sekonic and they seem to hold up great. Can't really see a difference more that 1/2 a stop. The best part is it keeps reading without pressing a button. The data changes as the light changes. Glad we only rented the Sekonic as this works just as well.
Looks like we are getting close to having a real product. Kickstarter here we come!