Struts and Spring integration was on our radar screen wrt to Struts Recipes and in real-life. My current favorite architectural combinations are Struts+Spring+Hibernate and Struts+Spring+iBATIS.
I think Martin Fowler is an excellent author. He's said that he writes to fill voids and gaps that have yet to be addressed. There is no point in covering the same topic unless there is some value to add. There are too many other things to write about. There comes a point when the author needs to pick and choose to provide the maximum benefit to the reader/purchaser. I think that is what we all want from a book.
With that in mind, I think Matt Raible is doing an excellent job discussing Struts/Spring integration in Spring Live. When you get down to it, it�s really Spring integrating with Struts, rather than the other way around. For that reason is probably better to deal with that from a Spring perspective than a Struts one. I applaud Matt for his decision to make the first chapter about Spring/Struts integration.
Leaving that topic out gave us latitude to discuss other topics that may not have been covered otherwise.