ryandotsmith/queue_classic — pull request #36 by freeformz (2012-01-10 17:23:51+00:00)
Title: promiscuous json gem 

This may be contentious, but the -> 1.6.1 json dependency conflicts with other gems we have in our Gemfile.

If not this, consider >= 1.5.whatnot.

This obviously means that if a newer json gem is releases that breaks their API (or is buggy as hell) there could be problems, but IMO it's up upstream to lock(via a Gemfile/gemspec.