No idea, but the thing about the GAAR!!!! (my "cool" sounding name for the Google Account Activity Report..) is that it validates my privacy settings.  I use an Android phone, so Google is pretty integrated into my waking life.  That means that all my searches, my SMSs, photos, where I go and when I go there are all potentially under Google's all-seeing eye.  My activity report shows that my privacy settings basically limit that information to the number of people who have watched my YouTube videos, how many emails I send and receive, and my most common email contacts.  Beyond that it's pretty blank, and the small amount of other info is pretty meaningless and inaccurate.  For example, Google thinks (through Latitude) that I spend 2 hours a week at work.  Yeah, right.  

I think it is worth checking.  I look once a month when the email reminds me about it.  More companies should make it easy to see what kind of information they are gathering about you.  While I still have privacy concerns, I appreciate that Google makes it more transparent that most companies.  Of course, they have much greater access to that information than other companies, so they should be more transparent, IMHO. Kinda the whole great power, great responsibility concept.