no thats not a real date. and even if it was nintendos actual release date had been delayed.
It would be perfect for me, because it would be in the middle of a vacation.the 27th of march would be a little too early for me, saved money for Portal 2, and i dont want to choose which child i like more...
The box art at least is fake.
full box art
It was fanmade.
I'm still trying to find that post you were referring to, and where the image you provided came from. Could you post a direct link? (double-checking about the release date.)
edit: oh, I see it came from a shoutbox. Someone who's registered there should contact him asking where he got the image from. For now, since the art is fake, I think it's safe to assume the date is fake as well.