There is no immediate plan of updating the book for 4.0, but I'm sure an updated version will come. 4.0 will definitely break a lot of the code. Zune for example isn't even supported using XNA Game Studio 4.0.
The best resources on 4.0 at the moment are Shawn Hargreaves and Michael Klucher blogs:
Once I have something to announce on a new book, I'll write a blog post. Unfortunately, at this time there is nothing concrete to announce.