"All the computer can give you is a manuscript. People don’t want to read manuscripts. They want to read books. Books smell good. They look good. You can press it to your bosom. You can carry it in your pocket."
The pre-numbered labels have not been restored yet since the new site went live at the end of May. You can still request pre-numbered numbers, though, in 10s or 100s, but you'll have to write them on a label yourself. There are a lot of links to great user-generated labels in this thread: http://www.bookcrossing.com/forum/7/358601. I believe JamesUK has some labels on his site that will number the labels for you.