O'Reilly is a technical publisher who is well known for selling DRM-free ebooks, and one of the eboks I have bought from them is called The Global eBook Market: Current Conditions & Future Projections. As you can tell from the name, it summarizes the global ebook market.
This is the type of book which will quickly go out of date (6 months or less, IMO), so it's a good thing that O'Reilly has released an update a few days ago. Or it would be, if I could tell what had been changed with the new edition.
There's no clear indication in the ebook where new content has been added, nor can I see where the existing content has been edited to include corrected facts or other details which only came to light after the previous update. There isn't even a change log for the update, so I don't even know which sections were edited.
Here is where ebook publishers could take a lesson from app developers. It's more common than not for app developers to post a list of what had been changed whenever they release a new version of their app. While the changelog is not always complete or accurate, it is better than not having one at all.
And yes, I do realize that I am preaching to the choir, given that a lot of digital publishers work with/beside/for app developers. On the other hand, O'Reilly is not posting these kind of details and if one of the more innovative digital publishers isn't then chances are they're not alone.
And besides, having this info in hand would really help readers, and that is the whole point.