Originally Posted by kovidgoyal
From this discussion I gather that the binary PRC format has not been reverse engineered?
It certainly has. Book Designer can read and convert PRC files so long as they are the original version. Mobi has a new compression method and files in that format has not been decoded but the original is well known. I put a link the wiki to a description. The original Mobi format is PalmDoc with some html constructs added.