There is a LOT to be said about this.

One of my first concerns is the movement of public posting forums from indvidual login to using single sign on (Facebook, Google, Twitter, Disqus, WordPress etc). The problem here (and especially with Facebook and Google+ which endeavor to force you to use your true name) is that your comments can be matched across a range of different sites. Each individual comment may not give away much, but if a potential employer, stalker, litigant in a legal case etc, can look at a lot of these postings a great deal of information can be leaked, and you have virtulally no knowledge of where and no effective way to stop it once it's out there.

That's one reason why I never post to any website under a multi-site account.

It gets messier. In the Feb issue of Technology Review, there is an extensive article on how big data drove the last presidential election. The article (uncomfortably positive in tone, as far as I'm concerned) focused mostly on the Democrats because they seem to have gotten the initial jump, and the data driven nature of the campaign. For example through a lot of deep computational analysis, they believe they have the identities of virtually all 69 million (theoretically anonymous) voters who voted for Obama in the 2008 election and also had identifying information on the hot issues for each of those voters, so they could target the campaign on an individual level. The article claimed this was a key part of their success in the recent election.

It gets wilder. In some areas they apparently identified a lot about independent and Republican voters as well through various techniques including purchasing anonymized cable tv records and using independent criteria to de-anonymize them. Factors as seemingly private as what was stored on DVRs were used to target messages.

This is positively creepy. We can be certain that the Republican party will not let themselves be caught unprepared again so there will be more of this next time around.