Personally, I think it will be during March, but later, so Adam's mathematical guess of March 25th is pretty good. Then again, I always predict things to come later than they do, so knowing Blizzard, they might drop it earlier in March. But your actual guess is up to you, of course.
Enter your comment on that post (not this one) before March 3rd, and be a US resident and 18 years of age or older to enter to win a game card if you pick the correct date (or are closest, or are one of four random people who picked the date, if there are more than four). Good luck everybody, and we'll find out the winner when Blizzard finally drops the new content patch!