If the Digital Economy Bill goes through (second reading today) it will potentially mean drastic changes to the copyright laws in this country that could result in any images you post to your website, Flickr, weblog etc, being used by anyone without the need to ask your consent. Under Clause 43, anyone using your work only needs to declare it an 'orphan work' by doing a cursory search for who holds the copyright and registering that they have done this. If you discover your work has been used, you can claim an as yet undisclosed fee for its use, but you have no right to stop its use.
For more in depth details, follow these links:
Other aspects of the DEB:
And on a related photography note, a campaign aimed at stopping photographers being branded as terrorists:
I'm a Photographer, not a Terrorist