When I think of where I am always seeing Canon, Nikon and Sony, I never see Olympus. The sole exception is the U. S. Open (tennis). Canikony has advertising all around sporting events and in sports magazines. The average person then thinks... "If I want a serious camera to get these kind of shots, I need that brand.
But I think the ultimate publication is the one that is most respected for photography. Sitting in a waiting room looking at all the glorious images (does anyone read the stories?) in "National Geographic", there are always at least one two page spread from Canikony and more smaller ads. These large ads feature glorious images in them too. The message sent is that you need thier camera to get these great photos. I know that there are National Geographic photographers using Oly equipment but the impression (with the average guy on the street) is that serious photographers only use Canikony.