We don't have an ebook, unfortunately, but if you have a Lynda.com subscription, you can watch the videos in my InDesign CS4 New Features title (there were tons of them):
http://www.lynda.com/InDesign-…..650-2.html
If you don't have a lynda.com sub (only $25 for a month), you can get a free week's worth of access by filling out this form:
http://lynda.com/trial/indesignsecrets
Also, in a pinch, the What's New section of Online help is always good because it summarizes the new features and links to the relevant parts of the online manual. Even if you skipped CS4 you can get to its online help file, here's the What's New page:
http://help.adobe.com/en_US/In…..C809a.html
AM