Apple will soon unveil the new iMac. John Gruber, a well known Apple blogger in a brief post at daringfireball.net, predicts that new iMacs will not support Blu-ray.
This prediction falls in line with Apple's focus on online movie delivery through the iTunes Music/Video store.
View source: John Gruber: https://daringfireball.net/linked/2009/10/04/ixnay-bluray