I'm a software engineer in Silicon Valley.
I design and build hardware plugins for iPhones and other smartphones.
Mobile phones are subsuming single-function portable devices. Alarm clocks, GPS navigators, calculators, digicams are now software applications on mobile phones.
I like the sample of a UPS delivery man. UPS amortize development costs over tens of thousands of custom handhelds they deploy. Apple amortize equivalent development costs over tens of millions of devices they sell. The UPS hardware may well be 1,000 times more expensive than an iPhone.
The particular specialty I am developing is building applications that require external hardware. One example of this type of product is my iPhly transmitter for radio control airplanes. As iPhly is entering mass production, I am developing a number of other hardware/software products.
My intention is to be the go-to shop for developing smartphone peripherals.