A new PNG spec

> Officially supports Exif data

Probably the best news here. While you already can write custom data into a header, having Exif is good.

BTW: Does Exif have a magnetometer (rotation) and acceleration (gravity) field? I often wonder about why Google isn't saving this information in the images which the camera app saves. It could help so much with post-processing, like with leveling the horizon or creating panoramas.

Yes, but websites frequently strip all or almost all Exif data from uploaded images because some fields are used by stalkers to track people down to their real address.

And I strip Exif data, too, intentionally, for similar reasons.

That makes sense to me for any image you want to share publicly, but for private images having the location and capture time embedded in the image is incredibly useful.

If you are uploading it to a website you are sharing it. Even if the image is supposedly "private" you have to assume it will be leaked at some point. Remember, the cloud is just someone else's computer, and they can do what they want with their computer. They may also not be entirely competent at their job.