These have been made (with the trackpoint replaced with a touchscreen + stylus), although you don't see them much nowadays. A examples would be the NEC MobilePr

These have been made (with the trackpoint replaced with a touchscreen + stylus), although you don't see them much nowadays. A examples would be the NEC MobilePro 900 (on the not-far-from-full-sized-keyboard end of the scale) and HP Jornada 6xx/7xx series (on the technically-pocket-sized-but-really-slightly-too-big scale). I regularly use a Jornada 690, with Linux installed, which I use to do some programming on when doing things like taking my mom to her doctors appointments. I don't keep mine in my pocket, but have a small bag, intended to be attached the front handlebars of a bicycle, that I attach to my belt, to keep it in.