Amazon would very much prefer it if you buy all your Kindle books from Amazon's Kindle store. That way they make more money off their suckers customers. In particular they make it very difficult to buy DRM-infested books from anywhere other than their Kindle store by obfuscating the key for the Mobipocket format DRM used and by setting a magic bit somehwere. Neither of these facts is terribly difficult to reverse engineer and indeed someone did so quite a while ago. The resulting python code has been very useful and linked to on a variety of sites such as mobileread.
In a classic case of DMCA abuse, however Amazon has sent mobileread a DMCA takedown notice to which they have complied despite reservations:
As some of you may already know, this week we received a DMCA take-down notice from Amazon requesting the removal of the tool kindlepid.py and instructions associated with it. Although we never hosted this tool (contrary to their claim), nor believe that this tool is used to remove technological measures (contrary to their claim), we decided, due to the vagueness of the DMCA law and our intention to remain in good relation with Amazon, to voluntarily follow their request and remove links and detailed instructions related to it.
It should be noted that Amazon seems to have changed its mind as initially it was rather more relaxed about hacking the Kindle. One wonders whether this is something to do with the Kindle 2 launch as the K2 is clearly a far less open product than its predecessor.
I don't really understand the logic behind this request though unless Amazon are trying to become a monopolist. As is noted on the mobileread thread I linked to above, Amazon owns Mobipocket and hence sells the DRM that other ebooksellers use for DRM-infested mobipocket. From previous research we know that Amazon gets a 5% of the list price for all books sold with Mobipocket's DRM so it's not like Amazon is failing to get any money from these other publishers. Indeed the ebooksellers that Amazon doesn't get money from are the ones that eschew DRM such as Webscriptions.
In fact Amazon ought to be making it easier for these other ebooksellers to provide Kindle content by allowing these ebooksellers to also create Kindle DRMed books, unless of course Amazon actually wanta to put these other sites out of business, If so then that looks like something that the FTC might want to discuss as David Rothman points out because it looks to me like a potential abuse of the DMCA and/or antitrust laws.
My suspicion is that the reason why they are doing this is not because it allows people to read Mobileread DRMed books on the Kindle but because it potentially allows people to read Kindle books on non-kindle readers (even though KindlePID.py does not, of itself, remove the DRM).
This bullying approach has had one clear negative effect. There are some 14 pages of commentary to the initial post on mobileread and most of it is negative. Mobileread is probably the main place where the early adopter ebook reading folk hang out on the web so annoying them looks like a PR booboo since these people are likely to recommend something else to their friends and relations. It has also now shown up at BoingBoing and probably will show up on other sites too. I should note that I personally will now be linking to BookDepository and other sites when I refer to books and that I will not be buying anything from Amazon if there is an alternative source. Furthermore I think it would be a good thing if this were copied elsewhere so that Mr Google's little workers make it easy to find and hard to remove from the internet.