Come on, where is your own initiative?
Surprise, surprise, it is called log4j.jar and located in the server configurations lib directory.
There is even one version in log4j-boot.jar located in the JBoss lib directory. This version is used for JBoss bootstrap logging.
Nope...it's in the $JBOSS_HOME/lib/jboss-common.jar.
Note how this is in the install wide lib directory and NOT the server specific ones.
Ups, my fault... reading JBoss logger and thinking of log4 logger... *grr*
Thanks rcostanzo, Frito