I think that delay has more to do with the Spore fiasco and SuckyROM/DRM mess than anything else. They can hardly afford another fiasco with their best-selling game; also, they are probably waiting to see which way all those lawsuits will be going. And if they sre not sure by June they will think of another excuse and move the date to September.
But worry not. We can all play Duke Nukem Forever while we are waiting.