Hmm, I really don't remember. I could have been via pip. But I'm guessing that I did whatever the install the instructions said because when I first installed ansible (and started using ansible) was just 4 or 5 weeks ago.
(And I must say, that in 4 or 5 weekends, I have completely rebuilt 2 years of chef work. Not only rebuilt, but everything is way way way way cleaner. No more chefdk, berks, uploads, chef server errors, complex resources-defs and impls, constant gem conflicts -- I could rant for hours. And on top of that I now create all the resources that our systems run on: aws security groups, elb, ebs, route53, etc. So I can blow away and recreate entire sub-stacks at will. My life is has been improved tremendously by ansible.)