I am not sure how much information Apple gets but if with an in app purchase of say a eBook, they get to know which eBook it was, it is creepy.

Apple really doesn't have to do any ad personalisation but still they are doing it as it is just more money for them. My fear is, eventually when they monetize more of their web properties, the data collection will increase.

While they might not allow others to sniff your data, they are in too much of a dominant position to not use it for themselves like the purchases data.

For me, this fight will always be, who will watch the watchmen? Regulatory hammer seems to be the only long term solution I can think of. As Apple's integration of hardware + software + software gateway + services, is just too scary and eventually will give them too much power.