The Iphone Kindle app is found in:
Code:
/private/var/mobile/Applications/743EF351-5848-4493-B752-1E49FA36BE51/Kindle.app
You will not find it in applications.

but I have a question, Where are the books stored? I want to put a PDF onto it without having to pay a 0.10$ fine for emailing it there.(As I don't use a credit card on amazon)