I know there's been some discussion in the past about images being rotated by 90 degrees, but I thought that I would add my observations.
We have an image field to hold a passport-style photo, ie in portrait orientation. Users who upload portrait photos taken with an iPhone (may be other phone types, don't know), result in an uploaded photo that has been rotated. To the user, on both the phone and importantly in Windows prior to upload, the photo was correctly orientated. Examining the EXIF embedded in the image, you can see that these photos have the orientation flag set to 'Top Right'. It appears that Windows (and any image viewing / editing software that I've tried) reads this flag and auto-orientates the image, but CB does not. To compound the issue, we have been cropping the uploads to our desired size - and of course for these photos, the crop is based on the wrong dimensions resulting in chopped heads.
The photo can be 'fixed' by editing the image prior to upload, and resaving it. This adjusts the orientation flag, and the photo uploads ok - but the user isn't going to do that, and doesn't suspect that there is a problem in the first place.
I suspect that this is how it is for now, but perhaps a future feature request?