A friend who uses Lightroom mentioned that LR now has "history tags" as he put it. Peeping at the XMP stuff in Smart Object files you now see XMP.did (document id) and XMP.iid (instance id) instead of the uuid (unique whatever... ) in CS3 files. Also you see a history reference.
What does this all mean? Is this just a new better way to handle the metadata, or does this imply we're going to see some history saved with the raw files in the near future?