As of now, Amazon has released the Amazon Kindle app for Android on the Market for free. The app seems to follow in the footsteps of the previously released iPhone and iPad apps in functionality. The first time you start it up, it will ask for your standard Amazon login information and then sync any purchased books accordingly.
One feature that appears to be essential in these apps is the bookmarking feature in that your spot in the book is saved no matter what device you are looking at it with. All of the other features including font resizing and background color choice are also available, making the app just as good as the other versions.
The best thing about this Amazon Kindle app? It now opens Kindle up to every major mobile and desktop operating system and puts Amazon in a very good place in the e-Book future.