akginty wrote:How about some kind of very cheap Radio Frequency (RF) transmitter/receiver.
Considering the Pi Zero is a good candidate for a high-function "Internet Of Things" device, very cheap comms would be fantastic. At a unit cost of £4 - 50 or 100 units would enable some very interesting "things" indeed. Imagine a network of solar powered devices dotted around a farm, measuring environmental conditions, detecting livestock and wild animals, spotting floods early, controlling targetted irrigation. And if a few got eaten by lizards or trodden on by cows, so what, they're cheap to replace, even on a limited budget.
Highly unlikely. The cost and effort of gaining regulatory approvals rules it out. It would no longer be a $5 device*. Also, as with the Pi 3, we would probably have seen the publication of FCC documents by now.
*Note that the cost of replacing a deployed Pi Zero with sensors, power supply, etc lost to mutant lizards or stroppy livestock is considerably more than $5 -- including labour, probably nearer $500.