They are implying that because you no longer need a PC to sync music or do updates to your iPhone that you won't need a PC again.
OK
So what kind of iDiot buys a PC solely for syncing their smartphone?
The post-PC era will only happen when the smartphone is a replacement for:-
Photo editing, and not just cropping borders
Video editing
Playing games, real games, not crappy Farmville
Anything that involves optical drives, read, rip, copy
Anything that involves hard drives or flash drives
Archiving and backup, 3G speed and 5Gb space is pointless when you have 5Tb of video
Home Theatre, when the smartphone can run XBMC and beam it to my TV, maybe
Programming, because fart-apps aren't going to write themselves
Porn, do you trust Apple to keep safe your stash of dwarf-pregnant-horse fap material?
It seems the idea of what the cloud is has become distorted, it was supposed to be distributed processing so that huge server farms could wield super-computer power to do tasks and just beam you the results via the internet, now it seems it has orphed into nothin more than online storage? Hasn't every ISP since the mid 90's offered online storage as part of your package?