I just participated in John Grden's online Papervision course found at Rich Media Institute.
It was a great experience. Lots of little gems to take away and apply to future projects. I think the best part is that many of these gems can be applied to Flash in general, not just Papervision. Altho there were plenty of Papervision specifics covered as well.
I had a little bit of an issue and missed the first hour because my comcast modem decided to die... which means I missed John's bongos ;) But I was able to catch up fairly quickly and I have access to the materials for the next 30days, plus I was given tons of example code to filter through.
All and all, I think it was a great experience and would recommend it to anyone looking into getting deeper into Papervision and optimizing their Flash files in general.