I've run into some snags with getting this script to work in Safari. At this point, the best option requires a shareware app that costs $10. I'm not really interested in paying for something I'll never use -- I use Firefox on my iBook.
Going the shareware app route would also mean that everyone else will need to pay the $10 in order to use the script on their computers. While the script is nifty, I seriously doubt that anyone will pay $10 for it. So, Safari is most likely out until someone writes a decent Greasemonkey clone for it.
In the meantime, I've been playing around with this: