I just read a ZDNet Article by Jason Hiner, and I strongly believe he is missing the point.
Before I delve into the details, I would just like to state my opinion. The browser has become frankenstein - these word processors (if you can call them that) and so forth are using the browser for things that it was never designed for. Sure you have V8 in Chrome now - but JS will never match real OOP languages like C# and Java in terms of maintainability. These are 'cool' things that should have remained 'cool.' Honestly, compare Google Docs to Word - I doubt a serious typesetter would consider using Google Docs. GMail is a great idea; Google Docs is an abomination. You need to know when to stop.
For the same reason, people are often fooled into thinking that the browser is the OS. His article is titled "Have we arrived in the post-Windows era?," however, do you see a single graph of OS popularity? Nope there goes the good old IE versus Firefox graph. That graph used to be relevant in the argument when people were complacent about the default browser on Windows.
His entire argument is based on browsers - and Firefox and Chrome install fine on my copy of Windows. He indicates that Vista and 7 bring nothing new to the table. Linux is still the same beast it was years ago. Sure you have Compiz now, but at the same time Vista has DWM - and it got a big question mark for that one. It is really hard to evolve when all the ideas are out there already; and I think Microsoft is doing a stellar job in that environment.
He says people use Windows XP because they are unwilling to upgrade to Vista. If people are using Windows XP does it not mean that Windows isn't reaching the end of its lifetime?
I wouldn't take that article seriously. He starts off claiming that Windows is dead, and then that all operating systems are dead. Typical web-head perspective - they never realise that you need something to run IIS/Apache/MSSQL/MySQL.
This must be the 20th article I read in the past 4 years claiming that Windows is meeting its demise (yes, even before Microsoft made a mess with Vista). Four years on the the corporate machine is still thriving; why? Because web-apps don't run without an OS dammnit!