Of course, when a Social Calendar user listed a friend's birthday or details of a holiday to Malaga, she or he probably had no idea the information would end up in the hands of a US supermarket. But now it will be cross-referenced with Walmart's own data, plus any other databases that are available, to generate a compelling profile of individual Social Calendar users and their non-Social Calendar-using friends.
The second decade of the 21st century is epitomised by Big Data. From the status updates, friendship connections and preferences generated by Facebook and Twitter to search strings on Google, locations on mobile phones and purchasing history on store cards, this is data that's too big to compute easily, yet is so rich that it is being used by institutions in the public and private sectors to identify what people want before they are even aware they want it.
The most important thing for data holders in the Big Data age is the kind of information they have access to. Facebook's projected $100bn value is based on the data it offers people who want to exploit its social graph. Its holdings include more than 800m records about who's in a user's social circle, relationship information, likes, dislikes, public and private messages and even physiological characteristics.