[Frenzie]

On the surface it doesn't sound like a morally wrong business model or anything. You buy a piece of hardware, you can do with it whatever you want. (So says the law, here in most of Europe anyway; maybe not in America.) Someone else wants to sell stuff for your piece of hardware that you can do with whatever you want? Sure, why not.

But risky because:

a. There might still be legal countermeasures available to Amazon. Duokan isn't the owner of my hypothetical Kindle, so maybe they wouldn't technically be allowed to sell stuff for jailbroken Kindles if Amazon doesn't want them to, even if I'm perfectly free to jailbreak my Kindle.
b. How popular can jailbroken Kindles possibly be? (Maybe the answer is millions upon millions in China… :P)