All this designer babble adds up to the same designer babble from a few years ago: that babble involved the necessity of designing for 640 and not even thinking of moving up to 800 because one of Genghis Khan's descendants in Ulan Bator might still have a mysterious metal box from the sack of Samarkand and not be able to view the site without scrolling.
What matters to me is that many of the biggest sites on the Web, including Yahoo, MySpace, and others, have abandoned 800 and moved up to 1024. Despite this 'improvement', these sites still draw untold millions of visitors.
The trend will continue. Many stragglers will move themselves up to 1024 simply because their favorite sites have begun designing for it.
Should you degrade the Web experience for the 90% of people able to enjoy 1024, or should you preserve the Web experience for the 10% who need 800 either because they're stubborn or they're unable to afford the upgrade?
Since there's no right answer to that question, it's something everyone will have to answer for themselves, without worrying about taking the 'wrong' position (there isn't one) or excluding a subset of the population from their sites (how many people are excluded from all sites because they can't afford a PC and an Internet connection in the first place?).