I just sifted through all of GitHub for YAML related projects. There were literally hundreds! Amazing...
I forked what I thought were the most important ones for shaping YAML2, and forked them here:
Please let me know if you know of others.
I forked 128 repos, which consisted of YAML processors for Ada, AS3, C, C++, C#, Clojure, D, Erlang, Go, Haskell, haXe, Java, JS, (node.js), ooc, Objective C, Perl, Perl 6, PHP, R, Ruby, Scala. Plus a bunch of neato YAML related efforts for things like search and schema.
With over 20 languages so far, I think our goal of having YAML everywhere JSON lives, is spot on.