You can use any yarn that takes your fancy for this, as the pattern is more about stash-busting, and how to estimate the size of the finished triangle.

My finished shawl took 4 balls of Veritas Colorado for the main part, and 2 balls of Zettl Cotton Classic Cable for the edging and fringe. It measures 24 inches along each short side, and 34 inches along the long side.

To finish, I crocheted an edging of double crochet mesh (US, single crochet) on the 2 short sides, and then added a fringe.
The PDF has now been updated, as of 19th March 2008, to give the full pattern for the shawl.