NWVault have posted an interview on Neverwinter Nights 2 with Ray Muzyka and Greg Zeschuk, BioWare's Joint CEOs. Although NWN2 is being made by Obsidian, BioWare supplies the engine and the original thought as well as design advice, technical support etc. Here's a snip:

1) What role does BioWare play in the development of Neverwinter Nights 2?
Greg Zeschuk : BioWare is providing the BioWare Aurora Engine to Obsidian to help build Neverwinter Nights 2. We're also providing technical support on the engine, as well as design advice. We're advising on the project so that the original vision of the game is passed on to the new team. We've got a good relationship with the folks at Obsidian and we definitely want to see them succeed in making Neverwinter Nights 2 a great game; we see it - in part at least - as still being a BioWare project.

2) Does BioWare have an approval in the final product?
Ray Muzyka : We're working closely with Atari and Obsidian as the game progresses and, at their request, we'll be assessing the game's progress with Atari as it moves along.

Read the whole thing (http://nwvault.ign.com/features/interviews/BioWareNWN2080604.shtml) at NWVault.