Yeah, if that picture has any accuracy, it'll be Java in Eclipse. I stare at Eclipse doing Java all day at work. That is definitely Eclipse and the format and length of the lines of code look like Java.
Is Amazon hoping/expecting big companies to buy Kindles in bulk for their employees to use these applications, or are they going for a large number of developers that already know Java so that development seems easier? My experience in big companies is that they don't buy new devices for everyone. It's more likely that a significant number of employees have to purchase devices outside of work and bring them into the office before the company considers supporting the device with applications.
Java is a safe bet for this kind of thing: you can sandbox things up pretty well and keep people from doing Evil Things. Also, it's pretty popular with Big Companies, so it's a likely bet for that reason as well.
