Superbit is a gimmick, most normal DVD's now are encoded at 'superbit' quality or higher. The article was mainly talking about when DVD first started making it's appearances and single layer disks were the norm.
At single layer, which was 4+ years ago for the most part, movies are encoded at lower rates. Even if they were double layer, they were still encoded at these lower rates to fit the extra's. And indeed, some dvd releases today use this scheme. But for the most part, since most new releases are multidisk, one for the movie, one for the extra's, superbit really isn't needed.
The poster before me mention's 5th element. While it is true that the superbit version of 5th element is better than the original version, the comparison otherwise is misrepresented. For example: Upscaling the 5th element and the star wars episode 3 would result in the same quality, with the edge possibly going to episode 3 since it's mostly, if not all digital, and since episode 3 is one of those double release sets, with the movie on one disc and the extra's on another. Thus, Episode 3 was encoded at rates similar if not higher than 5th element superbit.
Bottom Line: Don't think that superbit -gives- you quality, certainly not HD-DVD. In fact I would question the facts in that article from the first poster. DVD's max quality is 9.8 MB's, this is shared between both audio and video. There is no 'miracle' superbit encoder that makes dvd's look better than physically possible. Superbit therefore, should not be a deciding factor in a buying decision unless the alternative is limited to a single disk release, such as the original 5th element.