There are two really cheap small single board computers coming out, and while I haven’t yet had a chance to play with either, I have some opinions based on the specifications of each.
The Raspberry Pi Zero is a $5 slimmed down version of a Raspberry Pi. To get it running, you need a microUSB power supply and a microSD card. To view any output, you would need a mini-HDMI cable to connect to a display. To provide any input, or for any network connectivity, you would need a USB adapter, like a USB-OTG cable, and then the appropriate USB device. (Alternatively, you could solder something to the GPIO holes.)
The C.H.I.P. is a $9 computer which comes with 4 GB of flash, built in Wifi, and Bluetooth. To get it running, all you need is a microUSB power supply. All you need is a 2.5mm composite audio/video cable to connect it to a display. For input, you can quickly connect a USB or Bluetooth device.
Both computers run Linux on a 1 GHz processor and 512 MB of RAM.
At first look, the C.H.I.P. looks to be almost twice the price of a Raspberry Pi Zero. But before you can even turn on the Raspberry Pi Zero, you have to provide a microSD card. That card eats up most or all of the $4 price difference.
So for simple operation, the C.H.I.P. provides enough to get things working faster and cheaper. If I want to turn it into a wireless IoT-styled sensor, the C.H.I.P provides everything I would need to do that but the sensor. Whereas with the Raspberry Pi Zero I would have to add the microSD card, a USB-OTG adapter, a USB Wifi Adapter, and then the sensor.
However, the C.H.I.P. has a harder time competing with high-resolution video. By itself, the C.H.I.P. only provides low-resolution composite video. You can buy a VGA module for $10 or an HDMI module for $15. The Raspberry Pi Zero provides HDMI output with just your adapting cable.
The Raspberry Pi Zero also allows greater storage flexibility. Want 32 GB? Simply use a 32 GB microSD card. With the C.H.I.P., you would need to add USB storage.
So whether the Raspberry Pi Zero wins or looses over the C.H.I.P., depends on the application. But for many IoT applications, I think the C.H.I.P. provides more bang for the buck.