If iPad has resulted in the post=PC era, why did I see only laptops in the audience during the keynote? No matter what Apple tries to say, the iPad can't do it all.
I think Apple's concept of the post-PC era is a bit different to that in their eyes, the post-PC era means moving away from one device that can do it all, and moving towards multiple devices with specific purposes and use cases, all tied together by the cloud so that you can move data between them seamlessly.
I'm not saying they've got there yet, but I'm pretty sure that's where they're heading.