This appears to be what is now happening to me!
I am running the latest version of iOS7 and WordPress. Uploading images directly from my iPhone 5s to the site and placing them in a post. They show with the correct orientation when subsequently viewing the post on an iOS device (iPhone, iPad), but rotated 90 degrees on any computer (OS X or Win7). If I take the same image, rotate it in OS X, delete it off WordPress and re-upload, it shows up correct in OS X and Win7 but now wrong on iOS 7!
Anyone have any further luck with this?