I was making the point that you're basically looking a web page. You can do all sorts of pretty things which are going to help some books lay things out properly. Of course, that does require you move away from print layouts.
And
Bookworm supports MathML, I believe. Along with things like flash embedding for videos and so on.
Consider this, actually, for future potential: <canvas> tags in eBooks. It'd be possible to, for instance, embed math problems in the book text (And show text based on the current state of the problem - explaining common errors, for example, as well as say "click here for hint" areas, etc. etc.).