Ahhhh ... now I know a place to start for all of those confused grandparents who come in and say "But my daughter put the pictures of my grandson's birthday on the web, don't you know where they are?" I found Flickr very easy to use; I haven't used a web-based photo service before. Posting directly from Flickr to the blog went quite smoothly. I can see that libraries could use its resources to organize photos taken at events (or brought in by patrons) and then make them available to the public.
I don't know that I would use Flickr for personal photos. If I did, I almost certainly would mark them private. I wondered while watching the video if this sort of web tool has put some stock photographers out of business or if it helps them find new markets. I have a sister who is trying to start out as a professional photographer and that makes me wonder about the copyright implications of a site like this.