The answer, from the other HN post about this blog article (http://news.ycombinator.com/item?id=1355797):

"Well. We're talking about making this work in quite a number of different browsers, including IE6. So yes, it is." --matthiaskramm

(please don't vote up my comment; instead, give Matthias the points: http://news.ycombinator.com/item?id=1355880)