Thanks for bringing this subject up aiko, it was something I had always wondered about and now it looks like I will have to pay more attention than ever to protecting my work now that its online...grrr.
I wonder how much weight websites whose images carry a copyright logo over their artwork will carry these days, even with the usual please do not copy and distribute work herein without the creators consent. gotta hate right-click save image as
Its all very cut-throat....yarr!

Keep a weather-eye out mate