IBM has released the WebSphere Application Server 8.0 a month ago, and there will be a first RedBook "WebSphere Application Server V8 Concepts, Planning and Design Guide" coming out veeeery soon.
I had a pleasure to work on another publication, the "WebSphere Application Server V8 Administration and Configuration Guide", but it should be availabe not sooner than in a month. I would however recommend to read the concepts to get a felling of what have changed. And to be honest there were couple of changes - one of the biggest is that WAS8 will use the Installation Manager and Update Installer and Installation Factory has been fired... There is a lot that changed in the CIM also - it is smarter then before. And of course with JEE6 there are couple of new technologies like support for Servlet 3.0, EJB3.1 or bundled support for JPA2.0, OSGi 4.2.
I also have a personal feeling after working with WAS8 that you can feel some speed improvements - but that's only my impression after couple of weeks working with it.
You can read more about the new features in a great Developer Works article.
There is also new Rational Application Developer 8 with support for developing OSGi or SCA application with plenty of examples (1900 pages!!!!!!!!!!!! - ITSO record) "Rational Application Developer for WebSphere Software V8 Programming Guide" that you can get here.
Enjoy your book :-)