The difference is clearly illustrated on the screen capture. On the left, page visited using Google Chrome, my regular browser on my home computer. On the right, IE 9 beta, which I rarely use.
There are a couple of problems with the historical, cookie based advertising. The main one is that I already subscribe to both The Economist and Netflix! The second is if I click on The Economist one, it bring me to an offer for Americans only!
The advertising on this blog is now hardly worth the trouble ($100 in two years). Is cookie based advertising to blame?