ActiveFedora 6.7.4
Earlier today Greg Kellogg released a new version of the ruby rdf library (1.1.2), this breaks[1] the rdf-rdfxml (1.0.1) library which ActiveFedora depends on.
I've added a dependency in the active-fedora gemspec that ensures we get a working combination of those libraries. This is the sole change in this release.
If you are not upgrading to 6.7.4 it is highly recommended that you add this line to your Gemfile:
gem 'rdf', '~> 1.1.1.1'
[1] ruby-rdf/rdf#147
Later: Mr. Kellog has yanked the rdf 1.1.2 gem and released a fixed version (1.1.2.1), so this is no longer an issue.