One reason I continue to carry a device other than my iPhone is for ebook reading while commuting and traveling. Kevin Tofel posted some thoughts on reading ebooks on the iPhone using Amazon Upgrade that then prompted me to email myself a PDF version of a book. The PDF version is viewable, but emailing PDF ebooks to yourself is not the optimal solution either. I prefer to read Mobipocket formatted books, but I couldn't find any way to print these books to PDF.
Only Internet Explorer 6+ and FireFox are currently supported. You should download Firefox or use Internet Explorer to properly use the Flipbook viewer.
I then tapped OK and proceeded to view the book using the navigational buttons. Magnify does not work at this time in the Flipbook viewer, but you can simply use the two-finger Safari trick to zoom in on the text and the book is actually very viewable. Illustrations are shown and the book appears with a virtual book look. Since you are viewing in Safari you can read in either landscape or portrait mode, but with the way these books are setup like real books I found portrait mode to be easier to navigate. You will have to move around to read the book, but that is quick and easy with the iPhone. The Listen button is inoperable on the iPhone at this time as well. Search appears to work and you can see the yellow tabbed results, however as you move around the page I found it turning white and no longer showing you the results. There are a few texts that are available as full texts and if you want to read ebooks on your iPhone this may be another alternative, but you need to remember you will actually need a connection since the pages are downloaded as you turn them.