Google Might Disappear in Five Years
I use both a cell phone and a PDA. They simply have requirements that are contradictory with each other, at least until technology advances to where one can project images into the air.
For a cell phone, I want it to be as small as possible. This is so I can carry it around with me wherever I go.
My PDA, however, I prefer with a decently large screen. I have a 320x240 screen, and that's only because I don't want to spend more money. That way I can read things without having to either hold it really close to my face or hitting page-down every other line. I use my PDA to read books in a nice portable format [mobipocket]. I would not want to do this on the screen of any cell phone, and if you put a screen this size on a cell phone, I would not find it comfortable to carry around in my pocket [my PDA travels in my backpack, not my pocket].