Yes, it would be easy to make such plugin with the new features introduced in version 7.2.
Since objects can now be selected from the 3D view, a custom selection handler can be used to read the link from a custom property and take appropriate actions. Opening the URL in a new window would be trivial, but with some effort it could automatically download the image, import it as texture, and add a textured box at the proper location to show the image in the 3D view as a sort of augmented reality experience. The URL could be a web link, a local file on disk, or even a texture embedded in the model for max portability.