I'll just warn you, I might sound like I'm gushing, but I really can't understate the importance of what Paul Grilley has to offer to yoga teachers and practitioners. Every minute of that workshop was packed with information!
Skeletal Variation: I encourage you to go take a look at Paul Grilley's Bone Slideshow, which illustrates the variations in all the major bones of the human skeleton. This isn't showing deformities ... this is completely normal differences that you would see from person to person, every day. Paul's message is that the alignment rules cooked up by the various schools of yoga and teacher training programs are simply not going to address skeletal variation. As practitioners and teachers, you must recognize this and understand that you will have to move in a way that works for your own body.
Here's a short video clip from Paul's Anatomy for Yoga DVD that illustrates compression in the shoulder joint, which is an example of skeletal variation:
Yin is good for you: Your ligaments are under constant contracture and it is perfectly safe and healthy to gently stress the fascia by holding poses passively for a long time. Yes, I have been told that it is "unsafe" to stretch your joints, and that hyperextension is dangerous and you should never ever do that! Paul makes a very compelling argument, backed up by scientific evidence that it is, in fact, healthy and good for you to stress your ligaments. Aside from that, my own personal experience: practicing yin yoga has completely rehabilitated my tweaked out sacroiliac joint.
Each day, we did a practice, and then in the afternoon, there was lecture time, which included slide shows (like the one linked to above) as well as analysis of skeletal variation within the workshop participants.
The practices were great. We held the postures for five minutes at a time (usually). While the catalog of yin poses is pretty limited, we still did a different practice every day, which was interesting. One day we did a little yang warmup, and some yang between the poses, then one day we did straight-up yin without any warmup. The third day was definitely the most intense. We did a yang practice and then in the yin practice, we repeated postures, which meant a total of ten minutes in caterpillar (forward fold), ten minutes in snail (plow), and ten minutes in saddle (reclined hero). Then the fourth day, we were able to choose the most effective poses for our own body, and the fifth day, we did the "infant" series, which started on the floor and ended with yang. This gave me some ideas for my own classes and how to introduce variety, however, I must admit that my favorite way to practice is just straight-up yin, no warmup! It's hardcore yin! Kinda.
Paul and Suzee are both fantastic teachers. They went through a tremendous amount of material in 30 hours, and they presented it in a way that was easy to absorb, and with good humor. I left with a better understanding of anatomy in general, and I also feel like I improved my "X-ray vision," which is to say that I feel like I might be able to read my students' bodies better so I know what adjustments to suggest. I feel like every yoga practitioner, and certainly every yoga teacher, should view both the Anatomy for Yoga and the Yin Yoga DVDs and see what Paul Grilley has to say. He doesn't travel too much these days, except, apparently for 100-hr YTT he's now offering, but if you have the chance to take any kind of workshop with him, DO IT! You will not be disappointed.