Amazon have released an updated version of the iOS Kindle app taking it to version 4.2. The update has a new table of contents view so you can view your table of contents from the left panel menu within the book. Also in the update is an updated X-Ray feature, you can now select a word or name and look it using X-Ray.
The app is free from the iTunes Store
What’s New in Version 4.2
● Table of Contents: customers can now access their table of contents from the left panel navigation menu from within most books and see chapter headings and page numbers. Curious readers can tap a chapter to navigate directly to that part of the book.
● X-Ray Smart Look-Up: Look up Amazon exclusive X-Ray information without ever leaving the page. Select a word or name and learn more about the concept, person, or place in the Info Card provided at the bottom of the page.