It depends. I kind of agree with Austin on the whole Computer GFX not being real are, but I don't at the same time. I've done some pretty amazing pieces (the Buck being my best one) and I've done some very shitty ones (see my oldass sigs). But the thing is, with my Buck I actually drew everything and colored it in via Photoshop, so that in itself is art.
Could I do it on an actual canvas? Probably, but it wouldn't look as precise looking. I've done some pretty neat looking pieces on an actual canvas as gifts to friends and family, but none were as complex as the Buck I did.
I guess the main thing I'm saying is that a lot of it isn't art. A lot of the shit that people make in PS and such, it's all computer designed. You open up a render or something (that you didn't do, you just edited some shit in Bryce or C4D) and add some stuff to it. That isn't exactally art like most would thing, but it's art in it's own way.