do you have a paid account or a free one?
i use PB but only for stuff i don't want stinkin up my flickr site!
then i can post them on forums and stuff.
i believe jesse is right, they almost all run on the 'honor system' i think. i read alot on flickrs about stolen photos so it happens quite regular.
to answer your question tho,, no,, i don't see anything when i upload to PB.