The CIDER Session today (September 16, 2015) by Rory McGreal on Why Open Educational Resources? (https://landing.athabascau.ca/groups/profile/289790/canadian-initiative-for-distance-education-research-cider/tab/359765/sessions) is further validation of the importance of generating open e-textbooks.

An OER site -  http://epub-fhd.athabascau.ca  - offers students the opportunity to download an open e-textbook in the format of their preference.

The first e-textbook to be developed and deployed on this OER site is:

Creative Clinical Teaching In The Health Professions

http://epub-fhd.athabascau.ca/clinical-teaching

(It is noteworthy that the author(s) previously published an OER e-textbook on a similar system
- Supporting Individuals with Intellectual Disabilities & Mental Illness -
http://opentextbc.ca/caregivers )

Both open e-textbooks employ the Pressbooks plugin within Wordpress.  Pressbooks/Wordpress offers a publishing tool set that supports the spirit of OER - open and free - while being stable, and in active development.

According to some sources ^(1,2) , more than a quarter of the planets human population will be using smartphones in 2016.  A device that ubiquitous is a fantastic opportunity for epub e-textbooks.

Billions of smartphone users can't be wrong...

References:

(1) http://www.telegraph.co.uk/technology/mobile-phones/11287659/Quarter-of-the-world-will-be-using-smartphones-in-2016.html

(2) http://www.statista.com/topics/840/smartphones/