You are right, I would not consider a device with a 5" screen a "pocket" sized internet tablet. For example, I had a 3.5" Garmin gps. Then I bought a 4.2" one, much bigger screen. When I later checked out 5" gps receivers, they were just too big to be carried around in my pocket. If I were 6' 5" and 280 lbs, my bigger pockets would probably hold a 5" device.
Too bad there's no possibility for anything other than an "Internet Tablet" or a "really good smartphone". Because I can't get the N900 to fit into either of those pockets.