As a result of the settlement of the Gawronski et al. v. Amazon.com Inc et al. case (about the deletion of George Orwell e-books), Amazon.com will comply with new rules regarding deletion of digital works on Kindles.
Here's an excerpt:
For copies of Works purchased pursuant to TOS granting "the non-exclusive right to keep a permanent copy" of each purchased Work and to "view, use and display [such Works] an unlimited number of times, solely on the [Devices] . . . and solely for [the purchasers'] personal, non-commercial use," Amazon will not remotely delete or modify such Works from Devices purchased and being used in the United States unless (a) the user consents to such deletion or modification; (b) the user requests a refund for the Work or otherwise fails to pay for the Work (e.g., if a credit or debit card issuer declines to remit payment); (c) a judicial or regulatory order requires such deletion or modification; or (d) deletion or modification is reasonably necessary to protect the consumer or the operation of a Device or network through which the Device communicates (e.g., to remove harmful code embedded within a copy of a Work downloaded to a Device). This paragraph does not apply to (a) applications (whether developed or offered by Amazon or by third parties), software or other code; (b) transient content such as blogs; or (c) content that the publisher intends to be updated and replaced with newer content as newer content becomes available. With respect to newspaper and magazine subscriptions, nothing in this paragraph prohibits the current operational practice pursuant to which older issues are automatically deleted from the Device to make room for newer issues, absent affirmative action by the Device user to save older issues.
Read more about it at "Amazon Settles Kindle '1984' Lawsuit" and "Amazon.com to Pay $150,000 to Settle Suit Challenging Take-Back of 1984."