So IGN posted an interview with Snyder on the upcoming film. Link is:
As the title says, there will be no kryptonite present in the Man of Steel movie.
Personally, I think this is a very good thing. For starters, Superman's opponents are Zod and Faora, so there is no need to have kryptonite present to bring Superman down in power so that someone like Lex Luthor can get the better of him. Second, I think the previous films focused far too much on the use of kryptonite and even most writers are unable to properly use the weakness in an effective manner (though I did think its use in Superman Returns made for a nice dark twist when Supes was getting kicked around by Luthor's thugs).
Though of course successive films could bring kryptonite back into the fold, it could be nice if it never came up in the new movie universe and instead the focus of weakening Superman followed the creation of red solar radiation as is the case in the second issue of Superman - Earth One. Trying to make weapons that simulate a red sun would be the perfect reason to bring Lex Luthor fully into the new movie universe as the man the government turns to to head the project (wouldn't even mind if they did the mr. and mrs. luthor thing from Earth One and Lex at first has no quarrel with Superman and is simply fulfilling a contract but the death of his wife as a result of a battle or action taken by/against Superman is what creates their legendary hatred) and thus bring Lex's character in-line with the comics rather than the "criminal mastermind" Hackman and Spacey played (of which both gave superb performances but in the end the over-the-top schemes are far too juvenile for the type of superhero films that audiences demand today).
I mean, do we want to see successive Superman films where he's brought down by a kryptonite necklace and simply writhes on the ground/passes out or do we want to see awesome action scenes of Superman getting surrounded by opponents with red solar guns and slowly having his powers drained as he struggles against superior numbers? My money is on the second being far more exciting and also a far better way to show Superman having to adapt and survive a situation rather than what we've gotten in the past of Superman either being at full power and invincible or crippled and incapacitated by kryptonite.