Apple pays for most of its product placement....you think they didn't pay NBC a dime for 10 years of Macs in Seinfeld?
The reason they cover up the apple logo is because apple never paid them and they don't want to pay apple so they cover it up, its a fact that apple anything looks 10x better than anything windows, thats why there is widespread use in TV.
On the other hand Apple pays movies for product placement, anyone seen the previews for "Fever pitch"? Just in the 30 second spot there's a powerbook, G5 and apple display. They paid for that, and in Blade Trinity there were tons of apple products and the list goes on and on.
Not to sound racsist at all but I think that Apple tries to advertise to "White" people and sony tries to lure in "Black" people...In Hitch there was only sony things, TV's computers, displays everything was sony. Same in Guess Who. More black people are probally going to see those movies than say Fever Pitch where there is apple placement.