You see all these new products coming out with their own SDKs, allowing their users to add functionality to their gadgets as they wish. It begs the question whether Kindle needs a SDK as well.
The upside for the Kindle is huge. The potential is there, and with a better adoption rate, Amazon Kindle can truly achieve legendary status (maybe not iPhone level but close to it.)
I do believe that Kindle in its current condition does not provide programmers with enough flexibility to add useful functionality to it. However, with an enhanced color Kindle 2.0, you could certainly expect Amazon to take advantage and release their own SDK. I guess we will have to wait and see on this.