Sorry for the late answer, just seen your reply.
Again I am thinking about emacs, there you could have multiple cork boards, with multiple Windows. So basically, you open a cork board view, which in the background has a cork board buffer. And in principle you can then open a second cork board window to the same buffer, so that you can lock at two different places at once.
As for how to implement it, I am not sure, my crazy first idea would be as a clip board on steroids. So you mark some text and a index card with the text appears in the cork board.