Version 3.4 of Amazon's Kindle app for iOS has been updated, and the headline feature is one that was previously exclusive to the company's own hardware. X-Ray, the content analysis function that our own Paul Miller described as "an index cranked to 11" when it made its debut on the Kindle Touch, is now available for textbooks on iOS devices. No word on whether it'll make its way to regular books any time soon, but the move is an encouraging sign.
Elsewhere the app now supports Japanese text more fully, with options for vertical text and manga coming just in time for today's local launch of the Kindle Store. If Latin script is more your thing, Amazon has also brought the Caecilia font over from its E Ink readers and given the option to display books in the fonts recommended by publishers.
Update: as pointed out by commen