I recently took up nude yoga myself. I mean, whenever I did it at home I was always nude but I actually found a class (which is no easy feat in Ireland, I'm pretty sure it's the only one in the country that isn't tantric). I've gotta say, I really enjoy it. The stretching is so much easier without the clothes, it feels far more natural and comfortable, and you can see exactly how the instructor is moving to correct yourself.
The classes were started by a woman called Ishtar (shout out if she ever reads this) and I have to say that they are just excellent. I really hope the practice becomes more popular and commonplace because I'd love for it to be like saunas in Europe so I could take my non-nudist friends without them being too weird about it.