Recently AOL had a little "oops." They released 3 months' search data for over 650,000 subscribers. While they removed the AOL account names, they replaced those individual IDs with equally unique numeric IDs. Between "ego surfing" for one's own name and other specific local searches over such an extensive period, many of the "anonymous" people in this file could be identified. Theoretically this was supposed to be just for researchers, but they put it up on an unprotected site and naturally a whole bunch of other people found this Web goldmine. While they've apologized, there's no way to stuff the data back in the box.
Why do people care about the file? Several reasons. Search engine optimization consultants are drooling over the opportunity to compare search queries with the pages people clicked on. Since Google drives AOL's searches, their competitors now have a handy volume of data for reverse engineering their algorithms. Law enforcement has enough searches on illegal topics to keep them occupied for ages. The rest of us can simply be seduced by the life dramas captured in a season's worth of surfing.
Why should we all care about the release? If you didn't understand Google's resistance to disclosing this kind of data, maybe you can now see how personal it really is. Compared to regions such as the EU, the US already has very weak and patchwork privacy laws. And yet, it seems each week there's another attempt to erode them a little more. For some reason Minority Report is coming to mind, when Anderton (Cruise) was walking through the shopping center and every billboard tracked him as he walked by. If you think it's just SciFi, you haven't been paying attention to RFID developments.