IMHO, yoga is actually really good preparation (and cross-training) for climbing -- the particular kinds of flexibility and balance and focus you cultivate with yoga are a huge advantage in climbing.

And because yoga has so many poses (like downwards-facing dog) where you're bearing weight down through your arms, it helps balance all the pulling work the arm and shoulder muscles do in climbing, which in turn helps reduce the risk of shoulder problems.

I know a lot of climbers do yoga for these reasons -- I've heard there are even some places that run "yoga for climbers" classes.