I got this question from a colleague: "What does STC say about doc on eBooks?" I doubt that STC speaks with one voice, but I thought it would be interesting to pose the question here.
With ebooks (and other electronic formats) you embed movies, audio, slideshows, and other multi-media items. I've seen enhanced ebooks with Flash-based tutorials embedded directly within a "page." In my mind, ebooks are a replacement/alternative for *online* content (since it is self-contained, you don’t necessarily need a live internet connection) -- as opposed to printed material.
It is important to remember, too, that ebooks are not limited to stand-alone readers (Nook, Kindle, etc.). You can quite easily access an ebook on your PC. This makes it *much* more portable than traditional Help files (ever try reading HTML-based help on your Kindle?).
As to your original question of "what does STC say about docs in ebook format"... the answer is apparently "not much" .... See http://stc.org/component/search/?searchword=ebook&ordering=&searchphrase=all :(
There was an earlier discussion about user adoption with regards to ebooks: