Also, think of it this way: HD-DVD, Blu-Ray should not be solely equated with HD. HD is really simply a resolution, while HD-DVD and Blu-Ray are simply commercial formats. Remember the early DVD titles? The original Blade Runner dvd for instance? They look like really good Laserdisk ports, which they pretty much were, similar to the way that early HD-DVD looks like really good DVD upconversions. Comparing the original Blade Runner disk to the new one speaks of the leaps a single format can make, and when you extrapolate that to HD-DVD and Bluray Disk, which are both only now in the last couple months even properly utilising the disk space and technological capabilities of their format, its easy to see how much the images can potentially grow.
Also, consider this: HD is a fairly new format. SD has been around for decades. These early HD broadcasts of the last few years are comparable to the early SD colour broadcasts of the early 60's--compare those fuzzy, horrible images to the crisp, clear images of, for example, digital satellite movies with 5.1 DD sound. HD is brand new. HD-DVD and Bluray-disk, then, are like VHS and Betamax. Comparing HD to Laserdisk is apt, but really its not, because Laserdisk was a pivotal development that basically bridged the gap between VHS/Betamax and DVD. So really, the next-gen formats, the post-HD-DVD/BD format, will be equivalent to Laserdisk, and then the format after that will be comparable to DVD. One can imagine how good the images will look by then. And they will be the same resolution as the HD broadcasts that ESPN uses. When you saw Revenge of the Sith projected digitally, its an HD source--this is the potential that the format has to offer. Right now we are dealing with primitive commerical formats, and the results are impressive but unsurprisingly crude considering. I might not ever own a Bluray player because i probably won't own an HD television set for a long time but it is exciting to think where the technology may one day lead--and there are even efforts underway to develop 2K home projection technology, which is astounding.