I manage a blog at www.beedigital.net/blog , i haded PR6 and yesterday night i was invited to join and use ShoppingAds. For my surprise i installed the script, and after 10 hours i notice that my PR was now only 4. I´m going to take it off pretty soon i believe.
LOL Its not because of shoppingads.. google has updated PR yesterday... All sites dropped. Read more here http://forums.digitalpoint.com/showthread.php?t=513089&page=22