Mobile devices such as iPhones, Android-based phones, and tablets are gaining significant momentum as human user interface devices. The issue for me—and just about everyone else who uses full words when they type—is that getting information into those devices is very difficult. As such, they’re not useful as true business machines. I think that could change if we treat them more like games and less like computers.
Fundamentally, electronic devices are I/O (input/output) oriented, and the level of usefulness of any such device is proportional the efficiency of I/O. The computer (regardless of “coolness”) is a great I/O device because keyboards can accept information efficiently, and they have virtually unlimited output capabilities. The value of the computer is proportional to that input capability and the reason why desktops and (full-size) laptops are not becoming less popular as tablets and smart phones become more popular.