Julia has an interesting post on the Purification Program or (Purification Rundown as it is also called): The Purification Rundown
I have done the Purif twice, once in 1983 and again in 2001. The interesting thing was that the second time was after living in LA for 16 years, and the Purif took longer than the first time. Both times it was wonderful. Not only did I feel fitter physically, but I also found that I could think more clearly which made study and doing a job that requires a lot of mental work much easier.
It's also a blast, and you make some great friends in the sauna. I recommend it to everyone.