To serve static content under JBOSS 4.2.2, you should put it inside ROOT.war folder (deploy/jboss-web.deployer/ROOT.war).
Very often necessary to make an links to the some content, but not actually to copy it.
For this reason linux users do ln -s, to create an symbolic link to folder.
By default jboss ignoring those created links.
To fix this, you should add < DefaultContext allowLinking="true" > to the server.xml file.
Hope it helps to everybody, who is trying to run GWT compiler with JBOSS server.