JBoss Messaging Version 1.4.8.SP5 is a release made and tested exclusively for the EAP 5 only and it should be part of the JBoss 5 download bundle.
JBoss Messaging Version 1.4.8.SP5 is made specifically for a regression caused in 1.4.8.SP4. Please see the JIRA release note for details.
For full description of the contents please see the JBoss Messaging project JIRA.