You asked in the wrong forum (JBoss Portal is the old portal project, the new one is GateIn), I just saw this second message by chance :)
JBoss Portal Platform is fully supported by Red Hat and is based on GateIn. It goes through more intense QA coverage (by a dedicated team) and some immature features may be removed.
JPP 6.0 based on GateIn 3.5 is due very very soon now ;) You can already download the Beta on http://access.redhat.com
JPP 6.0 will be based on EAP 6.0 and embeds all of Java EE 6 standards, on top of that you have support for Portlets 2 (JSR-286), Opensocial gadgets, and WSRP 2.0 (to name some standards).