This is significant because in the past the limitations of EXIF have forced camera manufacturers to store information in a proprietary format in images, limiting its usefulness. But now that manufacturers are embracing XMP there is a chance that some of this information could be put in a more useful format.
For instance, it would be GREAT if cameras like the Panasonic DMC-ZS7 stored its location information (Country, City, State, etc) in XMP. Currently this information is stored in the maker notes, which means it is unavailable to most software. (The only reasonable option with the maker note solution is to use ExifTool to copy the information to XMP, which is one of the very useful functions of ExifTool, but in an ideal world this would not be necessary.)