what you must consider is before the n900 was widely known about as being in production nokia was marketing the N97 as a mobile computer too based purely on its form factor and active standby screen widgets.
so when you hear the words smartphone and mobile computer mentioned by nokia I'd take no notice b/c to me they cant differentiate the two themselves

EDIT: also i've heard nokia people say the N97 is not a smartphone, its a smartdevice.
so if nokia are not sure about there products you cant blame end users for having no idea.