It appears that the B-29 is in Boeing Bldg 2-40. This building is located along the Duwamish River next to Boeing Field, Seattle. Apparently the B-29 and a B-17 are both being refurbished in the old WWII manufacturing facility. Information that I have indicate that 9000hrs have been put into corrosion repair alone. While I cannot find indication of the B-29 being flyable, this woud indicate that it likely is not.
Boeing is providing use of the building until 2007. Boeing wants to tear the building down as it is unused. Boeing historians are seeking to acquire a portion of it to establish a museum of Building 2-40 and its colocation with the famous Plant 2 where more than 6,500 B-17s were produced.
For those unfamiliar with the plant, you might recall that Boeing (and the Renton city locale) were camouflaged under a overhead replica of a fake suburban area complete with houses, streets, cars, fake trees and shrubber and details all the way down to street signs and mailboxes. If you have never seen the city of Renton, you will have problems understanding the enormity of this ruse against the Japanese. Quite impressive.
Picture courtesy of Boeing archives.