As to what customizations JBossWS-CXF adds on top of vanilla Apache CXF, I'd say those are basically of two kinds:
- proper integration with JBoss AS (seamless support for EJB3 endpoints, JSR 109 v.1.2 impl [*], webserviceref injection in ejb3, JAAS integration [*] ...)
- JBoss WebService Framework (WSF) additions (support for JAXBIntroductions, common address rewrite, common jbossws management, common jbossws jaxws tooling, common jbossws api for using JSR-261, ...)
[*] completed in JBossWS 3.3.0, which should be released by the end of May 2010