Books.app is a simple eBook reader for the iPhone. It reads HTML and text files stored in your Media/EBooks folder, and is smart enough to enter subdirectories, if, for instance, you’ve broken a book down by chapters.

Changes:

Bug fixes! Books.app is now completely bug-free, and all features requested by users have been implemented. In addition, world peace has been achieved, Apple has announced that it’s open-sourcing the iPhone, and my children got A’s on their last report cards. Well, okay, that last one was an exaggeration.

http://code.google.com/p/iphoneebooks/