Getting slightly sick of all this to-and-fro myself, but if you're still hanging on the development status of Duke Nukem Forever, developers 3D Realms claim the game is still being worked on.
The disclosure can be found within court documents relating to the franchise, and specifically reads "[3D Realms/Apogee Ltd.] admits that it has continually worked on the development of the DNF for many years, and continues to do so".
In addition to this reveal, it seems publisher Take-Two began development of another Duke Nukem game, Duke Begins, in 2007. This title, however, was canned in April 2009, right around the time the publisher's support of Duke Nukem Forever dried up, leading to speculation that "Duke Begins" was as much a bargaining chip in negotiations with 3D Realms as it was a legitimate product.
Am I the only person in the world who reads all this and thinks "why?". This is Duke Nukem we're talking about here, not Halo. It stuns me that Take-Two continued to sink so much money (we're talking millions upon millions) into not Duke Nukem project (which this side of the 1990's was one too many), but two.