I may be seriously out of it, but is the web really evolving that fast? To me it seems more like release-race fanned by Chrome and Firefox. And the press releases are mostly about enhanced speed.
Real web sites care about stone age browsers like IE6 on XP. Or we would use SNI everywhere, and youtube would get off flash today.
I also see a lot of intranet web applications working solely with *old* browser versions. My favourite is one supporting Firefox 4 and 5 on Linux.
Funny that Jake talks about the Android model, where the browser is actually part of the stable base -- unlike desktop distributions, where it presumably will belong to the unstable/rolling department.