Wow, you definitely have some great ideas here, and given the enthusiasm about ipynb, I would not be surprised to see these things happen in the next 6-12 months.

O'Reilly does use docbook internally as part of the toolchain, but asciidoc is coming into style as well. I've done most of my work in docbook with a docbook editor, but did some of my latest boook in asciidoc, which was much easier. Just use a standard text editor of choice (like Vim) and get right to it. Much easier for me, anyway.

One thing I'd really like to see is ipynb supporting asciidoc instead of or in addition to markdown. You can go to/from asciidoc and docbook in a lossless way, IIRC.