The official KDK has been available for limited beta developers since February. Klab release said that they could not wait approval so that they built the emulator from Amazon’s specification documents.
Currently, not all Java interfaces are supported, but two main classes which are needed to realize key input and screen rendering are implemented.
As testbeds, two popular games – Tetris and Load Runner – are made on it. Tetris’s source code is also provided.
With the KDK clone, you may develop Kindle application before you can access official KDK. Although KLab does not mention it, Kindle applications may be able to run on this emulator (in your Java SE 6 on PC).