Mobileread has a good discussion of kf8 issues, and a python tool mobi_unpack.py (suitable for unpacking and understanding public domain kf8 files) at: http://www.mobileread.com/forums/showthread.php?t=61986 <http://www.mobileread.com/forums/showthread.php?t=61986&page=17> &page=17 It runs correctly and without any modifications or installation hassles on my windows CPython installation. I haven't been able to get it to run under IronPython, but then again I don't have much experience with IronPython (or with CPython, for that matter) If anyone else is interested in playing with KF8 (and presumably has a Kindle Fire and/or Kindle Previewer software) or in reading pleasingly formatted PG books on their Kindle Fire, I'm having good luck running PG html files directly through the new kf8 kindlegen, [as opposed to compiling a PG epub for example, or reading the PG version of the .mobi file] - especially if I take a minute or two to fix obvious html coding errors in the PG html files -- such as specifying side margins in the body.