Well, the situation is pretty simple now that Apple machines are based on X86 as the same highly optimized ports can be used that we have. Of course, we also have the PowerPC version for the 360. So VC-1 is not an issue at all.While OS X's DVD player application does support HD DVD partially, and OS X 10.5 Leopard should support the HD DVD disc format (and drives) natively, there is not yet full support for commercial HD DVD discs.
You should note that there is a big difference between us providing a full blown player (i.e. the case you are talking about) and us providing component technology for someone else who has the know-how to build Mac applications for a living. In case of Apple building the overall player or someone else with experience with DVD playback on the Mac, the situation would be much better than it was for us fending for ourself.
Our HDi code is highly portable and since PCs/Macs are pretty fast compared to embedded products, getting it running there is not a big deal. The bigger issue is someone building a secure implementation of the player on the Mac. This is the thing that always held us back. Without Apple's cooperation, it is very difficult to build a secure DRM implementation there. But I expect third-parties to get there, should there be enough demand on that platform for HD optical playback.
Judging by Mr. Majidimehr's comments, it sounds like we won't see immediate full HD DVD support (including DRM, HDi, and VC-1 support), although market demands mean that we'll likely see this sooner rather than later, possibly from a third party. Blu-ray support may come quicker though, as Apple has thrown its support behind the format, at least on paper.