Comment 2 for bug 570442

I haven't pinned down the problem, but under Ubuntu Netbook Edition 10.04 rc Nautilius it looks unrotated (portrait). I've looked at this picture under XnView MP picture viewer and looking for some info about EXIF data.
This I think is the place you should investigate. Some cameras have a built in sensor for portrait/landscape and info about that goes to exif data stored in the picture. The same goes to progras dealing with images. While some use exif data to properly present pictures, other don't. You can also alter exif data to change the information about orientation of pictures without altering the picture pixel data.
And this could be a reason for such different behavior.