By default a Seam application (from seam-gen) or copied from a sample, will display a welcome message on the first post-login screen. To change or remove this message, edit the messages_en.properties file (and any other translated message files). Find the entry for:

    org.jboss.seam.loginFailed

and either change it to an empty string to remove the message, or to whatever welcome message you want. Note that when I tried this, the change WAS NOT hot-deployable. I had to restart the app server to get the message to go away. The message resource files can be found in rCMS/src (where rCMS is the name of my project).