"The company quietly records many of the conversations that people have around its products.

The feature works as a way of letting people search with their voice, and storing those recordings presumably lets Google improve its language recognition tools as well as the results that it gives to people."

http://www.independent.co.uk/life-style ... 59376.html

Hmm, seems to not be very reliable. They had around 40 recordings from the last 12 months, about 90% of them were just wind noise and birds singing.