From Nate Hoffelder at The Digital Reader:
Reports are coming in from a couple different directions that the new typography, kerning, and other improvements that Amazon first announced in May] are tied to a new Kindle file format. Alles eBook.de reported yesterday, and a couple readers on MobileRead Forums confirm, that ebooks which have the new features also come with a file suffix of KFX.
Learn More, Read the Complete Post and More than 20 Comments