According to an article on joystiq:
Yes, folks, it's still alive and kicking - everyone's favorite vaporware is "in full production" according to George Broussard, co-founder of 3D Realms. In an interview with 1up
Here is a link to the article:

http://www.joystiq.com/2006/02/01/duke-nukem-forever-in-full-production/

lol...this game was all the rage at one time. It now probably even has its "cult" followers.

Wow. This game has got to be excellent...I mean, it's only what? 10 years late? LOL

No kidding, and it was "almost done" 10 years ago too...

I'll believe it when I see it.