The official Neverwinter Nights 2 forums have an explanation about the delay of Ossian's Mysteries of Westgate adventure pack from the project's producer at Atari.
My name is Keehwan Her and I am the Atari producer for Mysteries of Westgate (MoW) among other D&D products. Most of you know that the release of Mysteries of Westgate has been delayed because of ongoing development of a new security system. Near the end of MoW's development last year, we realized that the traditional protection of the .exe file would not work with it so we scrambled to find a reliable commercial method that would do the job. At the time, there was no solution that met our requirements. That is why, since the end of 2007, Atari has been working hard to develop a new security system that can be used not just for MoW but for all Atari products that need protection for data files without using the traditional route of wrapping the .exe file. Unfortunately, developing this system has taken longer than we anticipated and MoW's release has suffered as a result, because it is the first product that will use this new system.
Atari has been working closely with Obsidian and Ossian to try to integrate the new system with NWN2 and MoW specifically. Although we wanted the security modifications to go out with Update 1.12, it simply was not ready in time so we unfortunately had no choice but to push it into Update 1.13.