This is decent news for the HD-DVD camp, but I don’t think it is really earth shaking. Most Hollywood DVD releases are DVD9s these days because you have to over-compress video to fit on a DVD5. And 15GB isn’t really a big disc for HD content. So it is a real compromise. To try to release dual mode content they’d have to turn up the compression on both the SD and the HD content, to squeeze it into a smaller space. I think they would’ve been better off with a dual sided disc that is a DVD9 on one side and HD-DVD30 on the other.
But this is an advantage they’ll have over BD – BD’s different physical format means it is unlikely they’d be able to do this. Unless they have a way to put the BD content in front of DVD content – but I really don’t know if the red laser for DVD could see ‘through’ the content layer for BD without being too disrupted. Now, if it *can*, BD could have the advantage of having BD layers ‘on top’ of a DVD9.