Nest Thermostat Teardown
Nate 
The Electronic Bits
With the RF shield removed, we can finally see what lies within.
Here's what we were waiting for. This is an astronomical amount of silicon for a thermostat!
Here are a few shots in case folks want IC identifiers.
I haven't looked any ICs up yet.
But they should be out there.
This is the back side of the main board. Note that this was completely covered up with another RF shield. That seems odd to me as there isn't much here but decoupling and another anonymous IC that has been bonded to the PCB. Did Nest really believe there would be that much mechanical shock and vibration that they bonded every IC to the PCB?!
Here is a view of the inside front face. You can see that they covered the lower small aperture of the face with the characteristic PIR prism material. Checkout our motion sensor for a comparison. Ok, now take a step back and try to remember where all the screws, ribbons, and clips go. Astonishingly, the unit went back together within a few minutes - another mark of incredible DFM (design for manufacture).