Obsidian's Unannounced Game

The Feargus Urquhart Interview on GameBanshee talks with the Obsidian Entertainment CEO about the past, present and future. They talk about his days at Interplay, a little on the KOTOR series, Neverwinter Nights 2, Bethesda's Fallout 3, and more. Along the way he reveals they are developing an unannounced project:
We have been working on another title for the last four months that we can't talk about yet. It's going really well though and the team is really excited. It's using our own internal engine so we are really able to do things our way based upon everything we've learned about making RPGs in the past ten to fifteen years. Don't take that as a silent slam on Unreal - it's not. Our engine, like Unreal, is a tool and different jobs can be done better with tools that are made for them. There are things that our engine may never do as well as Unreal, but likewise there are things that our engine will do that will be better than Unreal.