AT&T has said that it is considering selling customers’ wireless and Wi-Fi locations, U-verse usage, website browsing habits (which means all sites you visit, even if you use "private browsing" modes), mobile app usage, and “other information.” In an effort to protect user privacy, AT&T says that it will sometimes bundle user data into groups, but that all data would be anonymous anyway.
To be clear, we don't have so much of a problem with the trade of personal data, meaning we give usage data and get something in return, like Google Now, just as long as outside parties don't get any personally identifiable data in the process. AT&T claims that will not happen, but it still makes us uneasy how much data our ISPs and wireless carriers can gather without permission, and often without an opt-out. With Google, you can always opt-out and delete personal data, but ISPs track everything you do, regardless of if you're using "private browsing" methods, and most people don't even realize it.
Although, from a public relations standpoint, it seems that not knowing is better, because there is always more of an outcry when Google is transparent over what it does, rather than ISPs who do even more, but aren't as open about it.