When I try to upload pictures that I took with my iPhone onto websites they upload sideways, but when I view them in iPhoto or Preview they show up how they were taken (portrait). Yes, I've tried turning the phone different ways, same result. Is there a reason that the pictures are showing up on iPhoto and Preview correctly but upload incorrectly? I've tried it both by using iPhoto and by downloading into Image Capture... same result.
iBook G4, Mac OS X (10.4.11)
Important note: if I read what you write, I don't think you changed the orientation property, you probably just flipped the image 90 degrees by having it rewritten from resolution size AxB to BxA. That's fundamentally different! In this case, the orientation tag can be ignored altogether (and as far as I know it will erase any existing orientation tag).