Tom, the cable is real easy and not expensive. (you may want to wait for an official release, if so ignore the rest of this message)

If you don't have (or want) a soldering iron, someone at radio shack or your home theater store would probably build it for you for $5. You can buy the parts at radio shack. All you need is:

1 female DB-9 connector
1 DB-9 protective cover
1 standard headphone mini-jack
a small spool of 4 conductor wire

download the drawing from prontoedit.com and you're there.