SK has not announced anything official, but MYM made a video interview with ReMinD, after the PGL finals, where he talks about his future and that he already left SK at new years and that a few players will officially leave at the end of the month. He also says that he will continue to play Warcraft 3 until Starcraft 2 comes out and then he will switch.

You can watch the whole interview here:  http://www.youtube.com/watch?v=xUVtQwdWOvc