Installed Apps
Interestingly, if you go to the website http://play.google.com/about/ and login using the google account you use on your phone, you'll be able to see all the apps installed on your phone ..
well ... almost ..
it shows you all the apps you've EVER installed on your phone, stating they're still installed, even if they aren't !!
So ... an app I installed months ago, and then removed, is still being flagged as Installed on the website.
So ... obviously google keep a record of EVERYTHING you install via Market, and with their new "one privacy policy fits all" approach, they'll probably start using those to target adverts at you !!
Biting the hand that feeds IT
