According to all the unofficial sites, it will close sometime in 2008 and will reopen with a new name, and menu. Not sure if they will also be changing the look of the place.
If its just the name and menu, it shouldn't take very long, but if they plan to fix up the restaurant, or redecorate, or have any problems to fix, then it can take longer.
So far, there has been no announcement as to when or if they are still going to close for the changes.
I also have a ADR for December 6th and am wondering what will happen if thats when they close. I'm pretty sure they will call you and ask you to choose a different place and they will make the ADR in the event that it closes.