Vaporeware 2006 : and the winner is ...

Wired awarded the King Of Vaporeware medal to ... Duke Nukem Forever :

Meanwhile, the grinning visage of Duke Nukem has practically become the official mascot of the Vaporware Awards. Sir Duke topped the Vaporware list in 2001 and 2002 after placing second in 2000. In 2003, we gave it the Lifetime Achievement Award in hopes we'd be able to stop writing about it.
But the readers brought Duke back in 2005, and he was voted King of Vaporware again in 2006. That's right -- two years in a row, three years after being retired from the list

But Scott Miller, CEO at 3Drealms does not look much worried about that:

"Thanks to the overwhelming success of Prey (our latest IP, and another game that took 10 years to release), we have been afforded another five relaxing years on the making of DNF"

I put two trailers of DN For(n)ever below, the first one was shown at the 1998 E3 convention, the second one back in 2001