I did some reading and asked some questions. Apparently it is called clabbered milk and used to be made often. It can only be done with raw milk, not pasteurized milk, because the pasteurization kills some of the bacteria that is needed to clabber the milk.
On a side note--that's why Clabber Girl baking powder was originally made. You would add the baking powder to clabbered or loppered milk to produce a leavening reaction.
Here is a link on how to make clabbered milk:
The Nourishing Cook
Someone on the Basic Cheesemaking Yahoo Group said they do this all the time. She freezes the results and it makes a 'killer cheese cake' during the winter.
I've got lots of raw goat milk in the fridge right now. I think I'm going to give this a try.