The above is correct as far as I know. One other alternative is to put some of your work in the creative commons:
Creative Commons
For those works that you *don't* want to retain exclusive copyright on, the creative commons is a great way to define what you want to let others do with your work.
A story:
I don't have any aspirations to be a professional photographer, but I like to try for a few good shots now and then. About a year ago, I put some of my pictures of our local drum circle on flickr, under a creative commons share-alike by-attribution license. A few weeks ago, someone from the drum circle asked if they could use the pics for their newsletter/website/etc. I was happy as a clam to share. For a professional photographer, I think the advantage of this situation would essentially be free advertising - the work is still attributed to, and owned by, the author. The drum circle doesn't have a budget to pay for photographs, so there isn't any revenue lost.