Another blow for Phorm and its user profiling technology: Amazon has opted out, preventing Phorm from monitoring their users' behaviour on that site. Phorm's business model is looking increasingly improbable given the threatened lawsuit from the European Commission.
I think the advertising industry has overplayed the benefits to users of adverts targeted based upon their browsing behaviour. However, this could be done in a privacy-friendly way by code running on the user's own PC, under their full control, retrieving customised adverts using Private Information Retrieval protocols that would prevent the leakage of any information on their interests to advertisers.
This seems an obvious direction for Microsoft and Google to go with their browsers, with the added advantage (to them) of capturing a further significant slice of future advertising revenues.