I wasn't familiar with this project, but the book makes it tempting to carve off a hard drive partition this afternoon and try it out. SELinux offers role-based access control and privilege escalation baked into the kernel, as described by the NSA:
This work is not intended as a complete security solution for Linux. Security-enhanced Linux is not an attempt to correct any flaws that may currently exist in Linux. Instead, it is simply an example of how mandatory access controls that can confine the actions of any process, including a superuser process, can be added into Linux. The focus of this work has not been on system assurance or other security features such as security auditing, although these elements are also important for a secure system.
One of my goals for Workbench is to offer more software and computer book reviews. If you're a publisher or author scouring the Web for press opportunities, let me know how to get on your PR mailing list.