Interesting project in Kick Starter about the biologic-electronics interaction. In this case a cockroach controlled with your iPhone. Well it is not so complicated, but it is very exciting. A simple PCB with Bluetooth LE (4.0 ready) module, I guess a TI CC2540, maybe from Bluegiga. Since it is BT LE, you can program any iOS device, and access to the hardware without paying the costly MFi homologation and authentication processor fees. BTW good news that Google stated that will support BT 4.0 natively, so soon available for Android I guess.
There are numerous news that I have been hearing that we are in the post-PC era, since Steve Jobs prophesied. Mmmmh ... well among some of my qualities I am dedicated to the complete design of electronic systems based on microcontrollers, in my case lately I am designing systems based on implementations of ARM cores by NXP. These processors are called SoC, System on Chip, which means they have a lot of integrated peripherals.