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:

Faster loading of files, and long files shouldn’t kill the program anymore.
View images from the file browser! Only JPG or PNG for the moment. Still no in-line image viewing. Sorry.

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