In previous versions of Photoshop, if you selected an area of an image that included an edge area and then chose Select>Modify>Feather, the Feather would be added to the entire selection. While this might be desirable in some instances, in the majority of cases, it would be ideal if the feather was only applied within the image (and not to the edges).
As a result, in the current version, the engineering team has changed the default behavior so that they feather is not applied at the edge (the canvas bounds) of an image.
Julieanne Kost enlightens us about this feature that I’m sure most people don’t even notice is there. Be sure to check out all her other awesome posts while you’re there, she has a lot of great information and tutorials.