On the dutch wikipedia I, together whit the others off cource, are looking out for possibel copyright violations of images.
There is a system where there is asked permission to the owner of pictures and the credit and the permission is included to the picture discription page.
The problem is users are importing pictures from other wikipedias whit a note like "from the English wikipedia" or "from the german wikipedia".
And when you look at that image on that wikipedia almost never there is a comment about the source of that image.
Also some Wikipedias have a different view about clear copyright violations, like this; http://sv.wikipedia.org/wiki/Tintin
I have to explain to a user of wikipedia NL that the image she has made by taking a frame from a televison broadcast not can be used. But it is very difficult to inforce a strong copyright policy when the other wikipedias are not taking the image copyright more serious.