Interactive ebook publisher Inkling has updated its previously iPad-only iOS app with support for the iPhone and iPod touch. Inkling 3.0 optimizes the layout for smaller screens and adds automatic syncing between devices, storing notes in a dedicated Notebook. The new app also lets iPhone users download only a chapter at a time in order to save space and data. It's free on the iTunes Store, but you'll need to create an account and spend between $5 and $200 for each book, depending on whether you're buying a cookbook or a medical reference guide. There's already a web app for Inkling, and the company hopes to both expand beyond its traditional textbook market and compete with Apple's own Author publishing platform. While students may not end up reading the Color Atlas of Histology on a 3.5-inch screen, the iPhone isn't a bad choice for some of Inkling's lighter stuff.