Not sure about the excitement for this device. Since an ARM-based version of Windows will break compatibility for all x86 code there doesn't seem to be a strong purpose for the device. Maybe for people without legacy needs since I am sure there will be updated versions of Office available. But otherwise it is practically a new OS without legacy support. It surely can't VM support since ARM just isn't that powerful.
iOS and Android, and now WP7 all had the same issue. If it's just a matter of recompiling, it's not going to be that big of a deal, particularly since phone/tablet hardware platforms from different manufacturers are so close to each other in terms of performance and capacity..