I had one with my last, have "officiated" over two, and plan on having one with this PG also.
They are such an amazing experience!!! Even the women who were very "mainstream" were moved and appreciated the experience. In a way it is as much a gift to the women who attend as it is to the expectant mother.
My ceremony included chants, birth bead ritual (I held the strand during labor), cornmeal massaging of the feet and a TON of other things. It would be too long to post all here. The full ritual is on my website:http://www.birthbeads.com/Blessingway.html
I will modify it slightly this time around: add organic sea salt to the cornmeal for cleansing and warm the mixture before massage (a great idea I got from a wonderful massage therapist in Calistoga!) and maybe cut a few things for time purposes (my first was Very verrrrrrrrrrrrrrrry long!).
Since this pregnancy is also my last, I definitely want to mark it with a special ceremony.