Game retailer GameSpot has announced that they will still be honoring preorders for Duke Nukem Forever from any time in the game's aeons-long long development history, all the way back to the beginning. So if you were one of the poor souls who said, “I need to make sure I'm able to get a copy of Duke Nukem Forever the moment it comes out! And while I'm at it, I'll upgrade my PC's RAM to 32 megabytes!”, you're in luck.
Though you'll presumably need to actually have a receipt from whenever you pre-ordered it, and I don't imagine many people hold on to 13-year-old preorders for legendary vaporware. So that's likely to be problematic, unless you're the sort of obsessive hoarder who lives in constant peril of being buried alive if the floor-to-ceiling stacks of windshield flyers, Trotskyist newspapers, Sears catalogs, and back issues of Datamation and Confederate Veteran that fill 95% of your house's internal volume ever lose structural integrity.
But if you are that guy, I wish you the best and hope the game doesn't disappoint.