Many netbook screens come in 1024x600, so I wouldn't plan for everyone to have 1280 columns just yet. TFA talks about mobile versions degrading gracefully, but not about desktop browsers on small screens.
You can get the exact same experience of a small screen desktop browser by shrinking your browser window, which it handles quite nicely.
The headline is misleading. The point of this layout is that we can go ahead and take advantage of large screen sizes without leaving behind smaller screens.
