There are a number of snapshot releases included in the current jbossas trunk build-thirdparty.xml as outlined in this issue:
http://jira.jboss.com/jira/browse/JBAS-3801
[starksm@valkyrie build]$ grep snapshot build-thirdparty.xml
      <componentref name="javassist" version="snapshot"/>
      <componentref name="jboss/aop" version="snapshot"/>
      <componentref name="jboss/aop14" version="snapshot"/>
      <componentref name="jboss/cache" version="snapshot"/>
      <componentref name="jboss/jbossws" version="snapshot"/>
      <componentref name="jboss/messaging" version="snapshot"/>
      <componentref name="jboss/microcontainer" version="snapshot"/>
      <componentref name="jboss/microcontainer14" version="snapshot"/>
      <componentref name="jboss/security-spi" version="snapshot"/>
      <componentref name="jboss/security" version="snapshot"/>
      <componentref name="jboss/test" version="snapshot"/>
      <componentref name="jboss/web" version="2.0.0.snapshot"/>
      <componentref name="jgroups" version="snapshot"/>

The JBAS-3801 issue either has a link to an existing issue for replacing the snapshot, or a subtask to replace the snapshot. Betas are fine. We just need some tagged release for inclusion in the jboss-5.0.0.Beta.