That's nice, but some guy's blog isn't exactly proof unless he happens to be a subject matter expert.
Here are a couple of articles which discuss ebook rights specifically
http://www.huffingtonpost.com/2009/1..._n_392687.html
http://www.copylaw.org/2011/12/who-c...ok-rights.html
https://www.lib.purdue.edu/uco/ForRe...html#reversion
What it really comes down to is what the literary agent negotiates. Even if you sign over all your rights, you can have the rights revert back to you after a period of time.
Katherine Kurtz mentioned that the reason that her first three Deryni books are in ebook is because a fan urged her to do it and converted them to ebook for free.