There may come a day, and rather soon I suspect, when the distinction between "desktop" and "handheld" becomes moot. Even now there are useful machines
http://www.gumstix.com/ and
http://www.damnsmalllinux.org/store/..._Small_Machine .
I can envision a pocketable machine with a screen that works just like today's Palm, but when you bring it into proximity with a screen and keyboard, it works just like a desktop machine. Wireless opens a realm of possibilities for such a device.