NWN2: Mask of the Betrayer - PAX 2007 Preview @ GameZone

This short preview put together for the Penny Arcade Expo is a general overview of the coming expansion for Neverwinter Nights 2. After discussing the developer's response to the community input, and some of the graphical content, they go on to mention some gameplay features:

There are also different planes of existence. Not only will players be able to adventure on the prime material plane, but they will be able to enter the shadow plane to fight monsters that are not visible on the prime plane...

Influence will play a larger part in this game as well. The demonstration of the game showed a party system reminiscent of Baldur’s Gate. Players can be very involved with party members, building influence and even convincing them to think along your lines.

Mask of the Betrayer is a lot more story driven and there is a lot more dialogue in the game. The spell effects showed not only solid graphical elements, but also a bit of a wry sense of humor.