Luke mentioned the Reload From button in the Manage Images dialog in his post the other day.
While preparing for my What's New in Revit 2015 session at the Revit Technology Conference in Melbourne last year (image above is from the session's handout) I found that it didn't work well. The Reload From button didn't replace the image when it is referenced in system and component families. It only seemed to affect images placed on their own within the project. It only seemed reliable when I used the browse button for the image through the image parameters in the properties palette (or schedule).
After reading Luke's post I went back to test it again, since we've had six web updates since then, and I was pleased to find that Reload From and Reload worked as I'd expect it to!
I then thought it odd that there is no way to just Place an Image, to place another copy of an image somewhere else in the project. By that I mean, the Manage Images dialog offers an Add button to load an image. If we've just or already loaded an image, the Manage Images dialog also indicates when there is more than one instance of an image in use. It would seem useful, to me at least, to have a Place Image button.
We do have Decals but they are really intended for a different purpose. We also manage the related images for them separately from the Manage Images dialog. I suppose it is easy enough to select an existing image and paste another copy elsewhere. If I'm not sure where to find it (which means I may not realize there is one) a Place Image button would be handy though. The available images ought to show up in the Type Selector?
Regardless the Reload and Reload From buttons in the Manage Images dialog makes it easier to revise an image and then show that revised version in our project. It's almost like an external reference. Almost, except for the automatic reloading when a project opens.