My quest for find ways to create rich mutli-media eBooks continues. As of today, I have not found any interesting authoring tools that are based on open-standards like the ePUB format. Several videos of prototypes for content delivery are floating around the interwebs, some of which I relays in a previous post here (see UPDATED: Popular Science's Magazine of the Future. Is this the Textbook of the Future, too?).
For months, I've been casting about for tools that will allow me to create mathematical eBook documents in the ePUB format. I chose that format because it's open, supported by the major readers (e.g., Kindle, Nook, iPad software), and can be authored in a way that's very similar to authoring HTML documents.
Here are a couple articles that demystify the ePUB format and show how it is related to HTML: