MacBook Air is such a bullshit marketing term. They should call it a "tiny computer box with a flippy screen"

So it's in fact not a bullshit marketing term, but an effective way to convey an idea that consumers wouldn't normally understand.

John Gruber.....is that you?

It's is the same it's always been: you develop against the worst browser that has significant penetration. From 2001-2008 this was IE6 and you were stuck with it, now that IE6 has finally dropped below 5% (my arbitrary cutoff) I can simply ignore it, and get mad at IE7 instead. Chrome 6 vs 12? Firefox 3.6 vs 4? Who gives a shit! As long as the IEs lag so far behind everyone else, they are the roadblocks and causes of confusion in web development. Not the minor differences between the actual modern browsers.