The Digital Photography School site has posted an article on “An Introduction to Creative Commons Licensing for Your Photographs” and whilst its a useful resource and I respect the work the Creative Commons organisation is doing, I have problems with marking any of my images in this way.
From both personal experience and that of my friends there seems to be a general belief that if an image is licensed with Creative Commons then anyone can use it pretty much however they want. Unfortunately this is not how the license works and at a minimum you are often required to provide a credit and link back to the image owner. Creative Commons is also frequently used to allow hobby bloggers, etc to use the image but to restrict commercial use. However again there have been cases where images have been used for monetary or commercial projects under the mistaken belief that Creative Commons allowed this.
As mentioned, I think Creative Commons is a good idea (in principle) however the organisation behind it needs to do a lot more promotion and publicity to educate people on the ground about how it works. In addition, its not clear what you would do if your license was violated. The Creative Commons team itself cannot provide legal advice or support. Finally, even the creator of Creative Commons – Lawrence Lessig – when asked whether using an image marked “Non-commercial” on a blog that contains, for example, Google Ads would be a violation responded “I don’t know”. This is due to the fact that many of these cases have not yet been tested in a court of law.
If you’re really worried about people stealing your work, then don’t put it online! However if you do, certainly for now, I would recommend using an “all rights reserved” note at least until Creative Commons is better understood and better tested.