Michael Gartenberg at MacWorld:
The iPad and other devices are not here to displace the PC (by which I mean all personal computers, whether theyâ€™re Macs or PCs running Windows). In fact, post PC means after PC, a new generation of products that build on the PC. What it doesnâ€™t mean is sans PC, that is, without PC. The personal computer will no doubt be with us for a very long timeâ€¦ but that doesnâ€™t mean weâ€™re not in the post-PC world.
I think soon enough post-pc will mean sans-pc for a good majority of folks: for many the iPad is their first PC.