I just found this post today. I had been wondering if a copy/paste feature existed. I often find myself looking up something from a book I'm reading using wikipedia.
To copy/paste a passage into a note or a search:
Start highlighting the passage the way you normally would, but instead of hitting the five-way button to save the highlight, hit the space bar. This will bring up a note box and paste the highlighted text into it. You can then save it as a note, or you can search your kindle, google, wikipedia etc.