From LinkedIn (Ebooks Discussion Group)
What is the best tool for converting iBooks to/from KF8 (within the constraints of legality and without hacking DRM?)
I guess there are two answers to this.
1. If the ebook was purchased from Apple and is being viewed in iBooks then it is highly unlikely that you will be able to convert to KF8 without “removing” the DRM on the iBook. (we can talk DRM morality issues later)
1. If the eBook is already unlocked (no DRM) then it is likely in PDF or ePub format and you can quickly convert to KF8 using the tool provided by Amazon (Kindle Preview http://www.amazon.com/gp/feature.html/?docId=1000765261)
Hope this helps