Apparently Amazon
Kindle users who highlight passages will now have a record of those highlights sent back to Amazon servers, where they will be compiled and sorted to help produce a new feature called "Popular Highlights."
[. . . .]
Amazon does not reveal preferences of individual users. Only passages highlighted by three or more users are included.
Bob Sullivan
The re-publishing and distribution of user-generated Kindle data should strictly be opt-in. That requirement satisfied, such information would be fantastic to see and share.
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