Google Nest Website: https://nest.com
Microsoft HomeOS: http://research.microsoft.com/en-us/projects/homeos/
Google Nest and Microsoft HomeOS are two different ways of looking at home automation. While Google Nest started with an intelligent thermostat, they have broadened their reach by focusing on other small parts of home automation. These systems include smart lights, smart power grid integration with home appliances, but through it all they only react subtly, and there is a large capital investment that must be made by the user to get a little bit of automation.
Study of intelligent thermostats completed with Google Nest:
http://www-personal.umich.edu/~rayang/links/NestStudy_RayoungYang.pdf
Microsoft HomeOS takes a different approach by not creating hardware that can specifically be used for home automation, but creates a software system that can integrate and unify pieces of hardware that have different communication schemas and a wide range of responsive variables. The key to a system like Microsoft's is that they have little control over the type of automation, or the vision of automation that their system will ultimately have.
Link to demo videos of projects created to utilize the platform:
http://research.microsoft.com/en-us/um/redmond/projects/homeos/homeos-demos.htm
Link to a comprehensive paper outlining the system architecture, software challenges and ultimate vision for the system:
https://www.usenix.org/system/files/conference/nsdi12/nsdi12-final149.pdf