Would the "Nest" thermostat work outside US?
Actually, you should be able to make them work in the UK. An electrically savvy friend of mine has one up for sale on ebay along with this note:

I would suggest that only the technology savvy avid DIYer, or keen professional electrician with enough research install this item.  Unfortunately because this thermostat is not intended for direct installation to common UK Central Heating systems, I will not accept returns.  It can be installed though!  It will work just fine when correctly installed, but there are the following caveats:


The Nest thermostat works on 24V AC North American HVAC wiring - in the UK most commonly we have zero volt contacts for Thermostats.  You can easily make this work with a 24V AC power supply and a relay after carefully studying the wiring.  The Nest draws a tiny current (12mA) through the coil to trickle charge its internal battery so I would suggest a good sized relay to avoid buzzing.
The WiFi in the Nest can only handle US FCC approved channels 1-11.  In the UK we allow channels 1-13, so just make sure your wireless access point is not set to channel 12 or 13.  No big deal.
You must skip the 'enter your zip code' stage of the setup process.  The Nest will not access weather data outside of the USA.  The smart algorithms still work fine without weather data - the sensors to check the temperature inside your house is what is most important anyway.
The Nest iPhone and Android apps to control your temperature from your phone are not available outside of the US.  If you have a rooted Android phone, you can install 'Market Enabler' to install the Nest app from the US Market and then it should work just fine.  I have no idea about whether such a thing is possible for the iOS App Store.


Once those four things are paid attention to, it should work well!  Would be a fantastic, high quality, high tech, rare addition to your home and definitely a cool talking point.