It's very frustrating if people 'steal' your images when you're a photographer. It's annoying if they 'borrow' them (hotlinking, use them in other websited), and it's downright evil if they are using them for generating money [1, 2, 3].
Anyway, on a 'local' forum, some of the members found out that Hyves.net members (you need to be a Hyves member to view this) were using copyrighted photos. Other 'Hivers' can use these images to create collages, or use them to 'pimp' their personal pages (yuk!!).
Some of the original images still showed the copyright info, while other photos were modified to remove the copyright text (deliberate copyright infringement if you ask me).
The 'fun' part is that people who use these images get mad if you ask them to remove the image due to copyright infringement. The general consensus seems that everything you put up on the Internet is up for grabs.
So, if you don't want others to (mis)use your photos don't put them online. If you have to put them online, make sure other people can't remove the copyright info without 'destroying' the photo (e.g. humongous watermark across the photo). Or just put very small versions of the photos online.