I presume that if you run a persistent world, then you cant make it pay-to-play otherwise you're illegally making money off someone elses product. Perhaps Bioware might sell licences? If not, then NWN will probably be the first massive online game that doesn't charge at all.
I don't know all the details though, so I'd like to clear up a few assumptions I've had to make.
As for the portals...well, they sound very cool. Imagine, linking two completely different worlds (different servers) and you can travel between them with the portals....Planescape anyone? That could be very cool...a Planescape mod, with a server for each plane.
Seeya
Andaar Amberfire
Lawful Good Paladin
Servant of Tyraeus
Resident of Avarus, otherwise known as Hell's Kitchen