I don't think you even can zoom in with the PS3. At least I haven't found any way to.
AVRat is correct though. If you want to watch 2.35:1 and greater movies without black bars get yourself this
thing. Course then any !.85:1 and lower content is going to have black bars on the sides. Which most people agree is worse than bars on the top/bottom.
Maybe with OLED the blacks will be so dark they'll blend into the panel seemlessly and it'll be like the bars aren't even there! "crosses fingers"