What you can do with mobile phone positioning data

This comes as no surprise, but there is a rich set of data concerning peoples' movements, habits, and behaviors that is being generated by mobile phone usage. This article discusses how it can be used to prevent disease outbreaks:
http://news.bbc.co.uk/2/hi/science/nature/7433128.stm

I wonder what the mobile phone companies are doing with this data now - they've had it for years. Mashup up with a map of retail locations, you could tell at which stores a person shops - which can then be used to infer political orientation (as shopping choices have been shown to be highly correlated with political leanings).