Along the lines what's happening with the Orphan Works legislation and why that's so important to oppose, here is an article that shows and talks about how Flickr strips out metadata, " ...including the all important copyright and other IPTC metadata that describe who created the photograph and potentially carry along a caption, title, and keywords for the image." from your files.
"Sure, when you're viewing the image on the Flickr page, you don't need that information. But when a user saves that image out to their local disk, or embeds a that photo in their own website even if it's being served out of Flickr's farm, there's no way to link that photo back to the maker."
Full article: http://duncandavidson.com/2008/04/fl...ht-metada.html
Not sure how many of saw what happened to Christian Dietz over on the ICPS boards where a company stole his CP pictures right off his website and made stamps, and then sold them.