WPsyslog2 is a global log plugin for WordPress. It keeps track of all system events and log them to syslog. It tracks events such as new posts, new profiles, new users, failed logins, logins, logouts, etc.
It also tracks the latest vulnerabilities and alerts if any of them are triggered, becoming very useful when integrated with a log analysis tool, like OSSEC HIDS. OSSEC requires the latest snapshot to properly analyze these logs: http://ossec.net/files/snapshots/ossec-hids-090826.tar.gz
More information, download, etc: http://www.ossec.net/wpsyslog2