Some will say that Apple's iPad is the be-all and the end-all of portable computing. I say nay.
Don't get me wrong, I'm a big fan of Apple. But look at the history. Datapads are not a new idea - Alan Kay's DynaBook and Mark Weiser's ideas of Ubiquitous Computing - both from the 1980's, with Weiser explicitly using the term Pad - predate the iPad by almost three decades. As much as I generally dislike Microsoft, their push for the "Tablet PC" probably led to some advances in hardware. Amazon's Kindle and Sony's reader both pushed hardware makers to build better screens and raised the bar on users' expectations.
And one important thing that Weiser advocated in the 1980's is still missing (full disclosure: I admit to being in the field long enough to have read his papers when they were originally published). In Weiser's world you could just slide a task you were working on from a handheld pad to a wall-sized whiteboard or to a wristwatch-sized device for storage, and things like active TCP/IP connections would automatically move onto the new computing platform. While you may be able to drag a project from a Mac OS application to a USB stick for storage, this is a far cry from having running applications movable from one computing device to another. People are indeed working on this problem, but a general solution is not yet at hand, as far as I know. It's not something you can buy today from Redmond or from Cupertino, at any rate.
Until this happens, our computers will remain isolated islands in the stream. Even if they are iPads.