Well, I coded my first "app" for the iPhone today, a very simple dealio that presents a list of text files (i.e. eBooks) and presents the one you click on so you can read it. These are eBooks on your phone itself, not the web! Hot darn!
At the moment it's very ugly and kludgy; you don't remember your scroll-point or anything, so if you leave the program to do anything else, you're SOL and have to start reading from the beginning. It only works with text files (no HTML or anything else). And there aren't any chapter divisions yet.
But it's a good first step.
I put a couple of screenshots here and here.