Support for O'Reilly HTMLBook conversions?

O'Reilly Media is developing a potential file format specification for authoring print and eBooks which looks like it could be an excellent starting point for high quality conversions to other formats. Is this something that make sense as a calibre supported format, and if so, is anyone working on this?

The spec can be seen at http://oreillymedia.github.io/HTMLBook/.

Thanks!