I've reviewed this plugin's code, and there is one major issue with it,
namely this line:

	system("hnb '$params{page}.hnb' 'go root' 'export_html $tmp' > /dev/null");

This could potentially allow execution of artibtary shell code, if the filename
contains a single quote. Which ikiwiki doesn't allow by default, but I prefer
to never involve a shell where one is not needed. The otl plugin is a good
example of how to safely fork a child process without involving the shell.

Other problems:

* Use of shell mktemp from perl is suboptimal. File::Temp would be better.
* The htmlize hook should not operate on the contents of `$params{page}.hnb`.
  The content that needs to be htmlized is passed in to the hook in
  `$params{content}`.

If these problems are resolved and a copyright statement is added to the file,
I'd be willing to include this plugin in ikiwiki. --[[Joey]]