Yes, the book does cover migration, and it makes the process of moving from 3 to 4 fairly easy since we were all in the process of transitioning while we were writing it, so there are a lot of "migration tips" that we included as we encountered related issues.
Dan Orlando Adobe Community Professional
Author, Flex 4 in Action (Manning Press)
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com