Note, starting mid April 2013, JBoss AS has been renamed to WildFly https://community.jboss.org/blogs/mark.little/2013/04/19/and-the-winner-is and any further nightly builds are now named WildFly builds and are available from here https://community.jboss.org/thread/224262
JBoss AS nightly builds (which represent the latest from the "master" branch at github https://github.com/jbossas/jboss-as) can be obtained from this CI job https://ci.jboss.org/hudson/job/JBoss-AS-latest-master/. Just click on the link under "Last Successful Artficats" :
to download the latest nightly build and start using it.
Any issues with the nightly build can be reported in this forum, in a separate thread.