Red Hat recently announced GateIn Portal. The business model is aka Sun's GlassFish Web Space Server.
Sun : GlassFish Web Space Server (Sun Java Portal Server + LifeRay Portal Server)
Red Hat : GateIn Portal (JBoss Portal + eXo Portal)
On one hand JBoss is specialist in middleware and was able to deliver a scalable portal with enterprise integration needs in mind, on the other end eXo was able to produce a full fledge solution on top of their portal. Read more here.
I would take "full fledge solution" as being more features-rich (especially those of social networking / collaboration context).
Sun Portal Server was highly scalable. We see it for ourselves as we were part of the Sun Professional Service team that deploy the Portal solution for the Malaysia's largest telecom 3 years ago.
However, in my own opinion, it is not slick. There is no "wow" factor to buy into a product like Sun Portal Server.
With the launch of GlassFish Web Space Server, the game play is different. When you talk to customers now, it's easier to pursue them into buying.
I hope the same goes to GateIn Portal. I'll be downloading a copy for evaluation internally.