I just saw another review of the OSSEC book, this time by Kurt R. Hinson:
In these days of tight and/or frozen budgets, utilizing open source applications has become a must for many of us in the security realm. OSSEC is one such “must have” application that will give you visibility and insight into Windows, Mac and Linux machines on your network through the use of this Host Intrusion Detection application…
Full review at amazon.com