Maybe not now, but soon...
Actually there IS a need for ONE device that can replace a cell phone, PDA, PMP, and Laptop.
One might observe that current UMPC's don't offer cell phone functionality. Until we recall that they DO have 3G or EVDO as well as Bluetooth 2.0. Skype and a bit of software are all that is needed to transform them into mobile phones.
UMPC form factor is prohibitive from a human factors standpoint. But we may well need to see the workplace evolve a bit before these devices come into their own. Imagine a not so distant future when all office desks are no longer equipped with a computer. Rather a keyboard, monitor, and docking station. When you leave the office your computer travels with you, in “portable mode” it serves as a PDA and phone. Aircraft seat back tables would have fold down keyboards with an embedded display and dock.
By making the “guts” of the computer user portable, we eliminate the need to constantly upgrade our workstations. After all, keyboards and displays have pretty much remained the same for decades. If the “guts” are with the employee, they aren’t left alone and unattended in an office. It also eliminates the need to transport data between computers, or between work and home.
And finally it eliminates the plethora of gadgets on belts, in pockets, and briefcases. Of course the loss of such an item could be disastrous, but the same could be said now for the loss of a corporate laptop or PDA/Cell phone.
Until then, they need a “few good peeps” to step up and help finance “the revolution”. Sadly I am a bit short of cash right now…… :-o