Are the $300 notebooks/laptops/netbooks included in the "PC" totals for other companies? If so, then you have to include the iPad. Because they can't do any more than the iPad does.
It's as portable as these small laptops (put it in a bag, but not a pocket), does what they do, and is in the same general price range.
Phones are even more portable (pocket size) than the $300 laptops, so they wouldn't be included.
It's really not that hard.