How about support for the input and conversion of eTextbooks formated in
the Wolfram (Mathematica) "Computable Document Format (.cdf). The
construction of the files looks, to me, like an XML/HTML based construct and
Calibre seems to work well with such ebook/document formats.
A look to the subject through the free eTextbook site,
http://www.ck12.org
should provide a start to see if it is practical to create a plugin for it.
This is in hopes that Ectaco's new Color jetBook can handle it, at some point.
Luck;
Ken