I'm sure many of you recall the Netflix Prize http://en.wikipedia.org/wiki/Netflix_Prize. This is that, for Wikipedia!
Although the initial goal of the Netflix Prize was to design a collaborative filtering algorithm, it became notorious when the data was used to de-anonymize Netflix users. Researchers proved that given just a user's movie ratings on one site, you can plug those ratings into another site, such as the IMDB. You can then take that information, and with some Google searches and optionally a bit of cash (for websites that sell user information, including, in some cases, their SSN) figure out who they are. You could even drive up to their house and take a selfie with them, or follow them to work and meet their boss and tell them about their views on the topics they were editing.
Here, we'll cut straight to the privacy chase. Using just the full history dump of the English Wikipedia, excluding edits from any logged-in users, identify five people. You must confirm their identities with them, and privately prove to me that you've done this. I will then nominate you as the winner and send you one million Satoshis (the smallest unit of Bitcoin, times 1 million), in addition to updating this thread.
I suspect this challenge will be very easy for anyone who is determined. Indeed, even if MediaWiki no longer displayed IP addresses, there would still be enough information to identify people. Completely getting rid of the edit history would largely solve the problem. In the mean time, this Prize will serve as a reminder that when Wikipedia says "Your IP address will be publicly visible if you make any edits." what they mean is, "People will probably be able to figure out where you live and embarrass you."
An extra million Satoshis for each NSA employee that you identify. A full bitcoin if you take a selfie with them.
Let the games begin!
Brian Mingus