I wrote a new blog post on my employers website about java and syslogging. In this blog post I describe how you can use the linux syslog service from a java application. I use Log4j to do the actual logging and I describe this configuration. Next to that, I also describe the basics of syslog-ng and how to configure it in a way that is useable by log4j.
http://blog.jteam.nl/2010/01/14/logging-to-the-syslog-from-a-java-application/
New blog post about syslogging from a java app using log4j