Nintendo made two Pokémon Game Boy Color's, a Pikachu Game Boy Advance SP, a Dialga and Palkia DS Lite, and two separate DSi systems for Black and White. I think it's safe to say that Nintendo will release a 3DS design for X and Y.
From what I know, they made a Pikachu + Pichu Game Boy Colour, celebrating the 3rd Movie. Blue Kryogre SP + Red Groudon SP. No Special DS systems for 4 Gen, only accessories. A Black Zekrom DSi and a White Reshiram DSi.