In an about face yesterday; MS indicated that it will either repair or replace ANY XBOX 360mfg prior to 1/1/06. Of course, the console must be faulty, and in need of repair. Not all consoles prior to this date is in need of repair, but MS conceeded that the repair rate was higher than the 3% than they are comfortable with.
See link here.
http://xbox360.ign.com/articles/734/734126p1.html