Laptops may still be number one for most travel writers, but apps like these make it more doable to accomplish some pretty thorough work from your iPhone or Touch.
iPhone Apps for Writing and Editing
TextGuru
According to Brancipater Software, TextGuru is an “advanced, desktop class, multi-function text editor.” With this app, you can read and edit Microsoft Word, Excel, and Powerpoint docs, as well as PDF files, in landscape and portrait mode. TextGuru features cut, copy, and paste, find and replace, autosave, a search funtion, web previews, and email capabilities.