Dave,

Last year I shipped a small number of worms (~50 mixed sizes) along with ~2 cups of the VC they were living in. This material had cocoons and very small babies in it. I put everything in a large styrofoam cup and filled it to the top with dry leaves. I poked a dozen small holes in the plastic lid. This then went into a box full of foam packing peanuts. I shipped it Priority Mail from CA to FL. It arrived 3 days later and the worms survived.

If you want to ship a larger quantity of worms, here's how the pros do it:
http://www.youtube.com/watch?v=LMXjIuDm3iU&feature=related

Note that if you do not harvest the worms so that they are one big gob of meat, then there is less need to use peat moss to provide separation between the individual worms. It is still important to make sure the material is moist, but a little on the dry side. Too much moisture could result in worms that get steam cooked if they encounter high temps for even a short time. Good luck.

Andrew