Here is a picture of my Zephyr swatch. It ended out measuring 12,5 by 12 cm (4,9" by 4,7") which is a little too large, so if I had smaller needles I would use 2,75mm instead of 3mm. From this swatch you can also see how much you are able to change the width and height just by blocking.
Purplejen has posted pictures of her Swatch One in her blog. Please remember the yarn estimate is based on her swatch (which is smaller than mine), so if you decide for a bigger swatch than hers you will need more yarn (estimate so far is 1650m). With her gauge the shawl will be app. 65 cm wide.