I have an interesting python script (not sure if it has been done before) It uses
import os
os.system("say %s" % say)
#and I have added;
os.system("say -v whisper %s" % say)
but now there are new voices in lion and i want to know how to get those voices and if there is a centralized list.

The manual doesn’t doc which voices are available. But I believe the syntax is just using the name like so:
I don’t have access to my Mac right now but I found this list from here:
There is also other languages as well.
UPDATE:
say -v ?spits out:If you do not see the voice you are looking for when you do a
say -v ?you can install more.