Finally, yesterday IBM published a draft version of a long awaited WebSphere Application Server V8 Administration and Configuration Guide. You can download it and review it here.
There is also first fixpack 18.104.22.168 available for WAS8 (http://www-01.ibm.com/support/docview.wss?uid=swg24030916). It introduces a Centralized installation manager sudo support which is not covered in the redbook. This feature facilitate installations using CIM and non-root accounts. This is the first fixpack, which will need Installation Manager to be installed in the WebSphere Application Server software.