1. Create a new server.
2. Select JBoss AS 6.X type.
3. Server host name: localhost
4. Runtime environment jboss-6.0.0.Final

Start the server, after a few seconds the following line is logged to the console:
18:15:59,325 INFO [org.jboss.bootstrap.impl.base.server.AbstractServer] JBossAS [6.0.0.Final "Neo"] Started in 14s:548ms
The server in Eclipse is in the started, synchronized state.

Double click the server and change the hostname to app1.local (app1.local points to 127.0.0.2 (=entry in %SYSTEMROOT%/system32/drivers/etc/hosts)
Save the server editor.
Click the open launch configuration. Notice that the -b option still contains value localhost.

Start the server anyway;
Following line will be logged in the console:18:29:23,539 INFO [org.jboss.bootstrap.impl.base.server.AbstractServer] JBossAS [6.0.0.Final "Neo"] Started in 14s:868ms.
Although the server is started, the server in eclipse still states Starting, Synchronized.

After 450 seconds the server gets killed by the timeout mechanism.
3 entries are logged to the error log of Eclipse
1)No message
2)The server was shutdown forcefully. All processes were terminated.
3)Server Official JBoss 6.x Runtime Server (1) failed to start.

Open the launch configuration via the server editor. Change the -b option from localhost to app1.local
Notice an error message appears at the top of the dialog. " The Host can only be changed in the Server Editor."
Save anyway, ignore the error message.
Start the server. Problem solved.

Wanted behavior:
Changing the hostname should also change the value in the launch configuration.
The name "hostname" in the server editor is also somewhat misleading. It also accepts 0.0.0.0 to bind on all interfaces.