[farmerbuzz]

The original author appears to be using an iPhone for prototyping, and clearly states that it is the "tablet form factor" that is making things so interesting. Even if they were using an iPhone there would be no point to putting the software on the app store as it would be useless without the appropriate hardware. (Edit: Just noticed author's latest post that yes they will distribute through the app store and sell an accessory. I stand corrected.)

In general, yes it is a bad idea to use consumer technology for devices with the sort of lifetime you find in the medical industry (often up to 10 years). Because of the high levels of regulation and testing, its not cheap to swap out a component for something equivalent when a manufacturer stops producing the one you originally designed and tested your system with.