Run Jboss AS 6M1, open the Web Console (not Admin Console).
You'll see:

org.apache.jasper.JasperException: Unable to compile class for JSP:

An error occurred at line: 87 in the jsp file: /ServerInfo.jsp
The method getServerBaseURL() is undefined for the type ServerConfigImplMBean
84: <h4>Environment</h4>
85: <p align="left"><font size="1"><b>Start date: </b><%=server.getStartDate()%></font></p>
86: <p align="left"><font size="1"><b>Host: </b><%=serverInfo.getHostName()%> (<%=serverInfo.getHostAddress ()%>)</font></p>
87: <p align="left"><font size="1"><b>Base Location: </b><%=serverConfig.getServerBaseURL()%></font></p>
88: <p align="left"><font size="1"><b>Base Location (local): </b><%=serverConfig.getServerBaseDir()%></font></p>
89: <p align="left"><font size="1"><b>Running config: </b>'<%= serverConfig.getServerHomeDir().getName()%>'</font></td>
90: </tr>

Kudos to Rado Husar.