Further development of RocketAMF has moved to github.com/rubyamf/rocketamf. Both the master branch and experiment branch are still available for use if you need them, but experiment users should switch to the new repo, as there have been some substantial improvements.
RocketAMF is a full featured AMF0/3 serializer and deserializer with support for Flash -> Ruby and Ruby -> Flash class mapping, custom serializers, remoting gateway helpers that follow AMF0/3 messaging specs, and a suite of specs to ensure adherence to the specification documents put out by Adobe. In addition, it now fully supports Ruby 1.9.