Slashdot reports on the recently disclosed patent application by Amazon.com for “Persistently storing and serving event data,” which describes a9.com’s personal search history feature. Admittedly, I need to spend more time studying the privacy implications of “personalized searching” – the collection and storage of my search histories. But one item from their patent application seems troubling:
 A Tag’s “undisplayable” flag may be used, for example, to allow users to effectively remove events from their viewable event histories. For example, the web site system 30 may provide an application 38 and associated user interface through which users can view and search their respective event histories, and “delete” selected events from such histories. When a user deletes a particular event (such as particular search query submission or browse node access), the corresponding event object is marked by the event history server 32 as “undisplayable” to prevent the user from viewing the associated event, but remains accessible to clients of the event history server 32.