On Saturday, the Slashdot community had a very colorful discussion about Edd Dumhill's excellent Metadata for the desktop article.
On a related note, the Mac OS X Tiger's Spotlight file search utility will be harvesting metadata from each file's metadata.
These are all great developments. Within the next year, I hope to clear up some of my own mental metadata about my computer's file system. What will I do with all of the extra space?