It turns out KF8 isn't all that new. I've looked at the code, and I'd call it an attempt to graft a number of Epub features onto the existing Kindle format. It simply adds a lot of new formatting and is only slightly more capable than Epub.
There's a number of screenshots at the link as well as a demo file. You can probably also find more KF8 ebooks in the Kindle Store; look for the Kindle Fire exclusive magazines and graphic novels."
Link to Original Source