RC6 has already been shipped with JBoss 4.0.4CR2 application server. I was on vacation when this went out and just got to putting the binaries together for the standalone distribution.
Things of note?
@WebService/jsr181 support. @WebServiceRef isn't supported yet though. A tutorial was added for it. Thanks Thomas/Jason.
Embedded EJB3 has security support now thanks to Carlo de Wolf
lots of bug fixes, see the release notes for more detail