Release 19 is out
Release 19 is done. It uses the iTextSharp library (which is why the zipfile is now way bigger) which allows it to generate PDF files without requiring htmldoc. The html to PDF conversion is fairly basic so you can still elect to use htmldoc if you want more sophisticated conversion (including TOC).
Release 19 can also generate RTF files with images.
I was hoping to have Gutenberg integration by now but haven't done so; nontheless I published a sample 'feed' which is an example of how you can use rss2book to format Project Gutenberg books for your e-Book device.