Dive Brief:

• Google recently delivered a letter to the Securities and Exchange Commission to explain that the reason it doesn't disclose revenue from mobile is because the definition of mobile devices is still in flux. 
• The words that Google used — "a few years from now, we and other companies could be serving ads and other content on refrigerators, car dashboards, thermostats, glasses, and watches, to name just a few possibilities" — has spawned speculation that it will serve ads on its recently acquired smart thermostat, Nest.
• Google later released a statement to the Wall Street Journal explaining that "Nest, which we acquired after this filing was made, does not have an ads-based model and has never had any such plans."

Dive Insight: 

While Google says that Nest has never had plans for an ad-based model, that doesn't mean that Google isn't planning something. Also, perhaps Nest wouldn't deliver ads directly to the thermostat, but the data collected by the smart device could easily be used in Google's bigger schemes for mobile advertising and targeting.