Here is the Duke Nukem: Forever teaser the internet has been buzzing about. There isn’t much to say about it because most of the minute long clip is just Duke pumping iron. A few flashes of combat show a ferocious looking Pig Cop, but there isn’t any gameplay footage.
The 1998 E3 trailer is a different story. It has plenty of live alien blasting, which probably doesn’t reflect the 200X (20XX?) version at all. For comparison’s sake take a look at the trailer past the break.