Something big just happened, something so imperceptibly big I almost didn't notice it.

I just upgraded a computer with one that is less powerful, not more. For as long as I've been using computers, which is about thirty years, each time I have replaced a computer, the disk or the memory or CPU has gotten bigger or faster. But this week I replaced a 2.4GHz Core 2 Macbook Pro with a markedly less powerful 1.6GHz MacBook Air with less disk capacity.

That's significant.

It means that after decades of continuous and linear performance upgrades, a high water mark has been reached and the classic, monolithic characteristics of processor power and capacity are no longer the principal influencing factors for personal computing experience.

And while I think we all implicitly get that; that we all accept that the smartphone and tablet form factors are relevant and important supplementary or complementary device subsets that are permanent deviations, and that time spent on web apps is increasingly displacing and replacing time spent on local runtime software, these are progressive and almost imperceptible shifts.

Like noticing one day that your kids seem to have grown three inches overnight, in spite of the fact you spend every day with them and clearly they haven't.

Sometimes you need to take a step back to see the big changes.