Here's an interesting post from Agent Kristin. She says, "Most authors, at this point in time, are not interested in walking away from a publishing contract over electronic book rights. The numbers are growing certainly (as we can see that statement to statement) but the numbers, in general, are still very small in comparison to traditional print sales."
She then goes on to talk about J.A. Konrath, and concludes that if an author doesn't want to walk away from a publishing contract over ebook rights (and most, she says, don't), "We find another way to protect the author. One method is to include language in the publishing contract that dictates that if industry standard changes in regards to electronic book royalty rates, then the rate can be amended or renegotiated in the future to adhere to new industry standard."
That seems like a good plan-- the best an agent is likely to be able to accomplish for an author. What this fails to address, however, is that the problem with letting a publisher have your e-rights is not so much about royalty rates as it is about the way pubs sell ebooks. Major pubs tend to price ebooks at unattractively high figures. Whether publishers do this to protect paperback sales, to cover overhead, or both, isn't really the issue. The simple fact of the matter is that readers don't like to pay as much or more for an ebook than they do for a paperback.
What Konrath has been saying isn't that he doesn't get adequate royalty rates from his major publishers, but that he can sell more copies and make more money on his own, due mostly to his ability to price his books to move. Major publishers can't or won't price ebooks cheaply, and making sure an author has a good royalty rate for e-published books isn't going to change the basic issue. That underlying problem is that authors can price their own books to sell on Amazon, and move them substantially faster than publishers can.
Now that Konrath and others have shown that authors can in fact sell a lot of ebooks, signing away your e-rights becomes increasingly problematical.