It's a label for a vision in which the traditional PC (Windows or Mac) isn't the primary computing device that people use most of the time. For example, a growing number of people don't need a PC to get on the Internet today: smartphones, iPads offer the easiest and most convenient on-ramp without all the overhead of owning a PC (weekly Windows updates, mandatory reboots, virus scanning, cleaning up temp files on your disk, rotating login passwords, updating drivers, running defrag, solving general PC problems). That wasn't the case 10 years ago, when mobile networks were terrible, mobile phones were crude and terrible at web browsing, wifi was non-existent, and tablets were heavy Windows convertible laptops with clunky pen input and unusefully short battery lives.
Yes, the laptop has made the PC more portable, but it hasn't reached and will never reach the level of pervasiveness of, say, pocketable smartphones. I can check emails and the web, or tweet without a PC while waiting in the checkout line. Instant-on, no waiting, always available. A traditional PC can't compete with that.
The post-PC era (as Steve Jobs used it) didn't mean the PC went away, as some Windows fans seem to think. Or that post PC devices had to do everything that PCs do to be relevant (the "it's just a toy" argument). It is simply no longer the only choice for doing the things that traditionally required computers. I would argue that for being connected to the web, it is actually better. And by Steve's estimation, the PC will one day be relegated to certain niches. The PC hasn't reached niche status yet, but don't be so quick to dismiss Steve's prescience. Doubters should bookmark this post and come back in 5 years when things have settled down.
Thanks for the reply.
So if apple ever merge OSx and iOS will it be a "Post- post PC +" device? ;)