I know a lot about this. Est (now called Landmark Forum) was a heavy influence on CEDU's propheets (and parent workshops). Lifespring (very similar to est) also had an influence (though WWASP's seminars draw on this more). All in all, est, LifeSpring, Actualizations, Mind Dynamics, and others aren't that different. Est is just one of many LGATs (large group awareness training). Read Margaret Singer's "Cults in Our Midst" for more information.
Margaret Singer and Richard Ofshe wrote a lot about LGATs and are probably who you want to be reading if you want to find out more.
Go
here for a Video of what goes on inside Landmark Forum (french with subtitles). Those who were in programs will probably find a lot of it familiar.