They've said it on a couple of occasions in the last few minutes on Sky Sports News, man. They just announced it briefly, accompanied by footage of him in training - they didn't make a big story of it.
I suppose when i think of it, he did seem a bit out of place as an assistant with Steve Clarke in there with Kenny. Sad to see him leaving the club. He'll probably be back again at some stage.
YNWA Sammy