The Amazon Kindle is an ebook reading computer that poses very serious dangers to society. When you purchase a Kindle, you are subject to Amazon's Digital Restriction Management (DRM), a system designed to take away rights you would typically have when reading a book.
Your basic rights to share, sell, or donate a book are subject to fights with Amazon over the legal and technological restrictions they try to impose. If you try to exercise these rights anyway, you might be violating the Digital Millennium Copyright Act (DMCA) -- which could bring severe criminal penalties -- and Amazon can try to revoke your ability to use all the books you've bought.
After you read a physical book, you can give it to a friend or sell it. Not so with a Kindle book. You can donate a physical book to a library -- an institution whose purpose is to continue sharing it for as long as possible. The Kindle's DRM, however, is designed explicitly to prevent sharing and the public benefit that institutions like libraries provide.
Amazon has a web page about e-book lending, which explains that only certain "lendable" books ("lendability" being determined by the publisher) can be lent at most one time, only within the United States, for a period of exactly 14 days. That's a pathetic (and failed) attempt to replicate what was always a very natural aspect of printed books.
In terms of strict analogy, Kindle DRM even prohibits you from moving your books to another shelf. Any DRMed book you buy for the Kindle is forever locked to your Kindle until Amazon decides otherwise (and they show no sign of wanting to give up that control). If somebody else makes another ebook reader (one that perhaps also gives authors a better deal) readers are stuck with the Kindle, unless they want to repurchase the books they've already bought. Like Apple and the iPod, Amazon uses DRM to create lock-in: they don't want you using competing products from other companies.
But the DRM affects you even if you don't try to copy or move your books. Amazon knows what Amazon books you have on your Kindle, and we strongly suspect that it also has the back door capability to view and delete non-Amazon books remotely as well. This is not conspiracy -- we know this capability exists because Amazon has previously deleted copies of 1984 from users' Kindles. It is only supposed to do this if it gets a court order, but do you want your books to be vulnerable to that?
This is why we have decided to rename the Kindle as the Swindle, and we invite you all to join us in tagging the Kindle and all of the the DRMed Kindle ebooks on Amazon.com with the phrase "Kindle Swindle."
 Even when non-Kindle ebook DRM schemes claim to let you "lend" ebooks to a friend subject to their terms, this isn't really lending. Your friend needs to identify herself to the ebook seller and enter into their own contract with the seller, and to have a particular kind of device. They aren't borrowing the book from you so much as entering into a peculiar and limited contract with the book seller.
How do I tell if a Kindle ebook has DRM?
At first, all Kindle ebooks had DRM. However, now there are some offered that are DRM-free. We want to be careful to only tag the DRMed ebooks as defective. Of course, Amazon does not make this easy. Some publishers will include DRM-free in their name, such as "Candlewick DRM-free". Otherwise, in the product details section, look for a line that says "Simultaneous Device Usage: Unlimited". That indicates an ebook which does not have DRM.