The most frequent question I get asked about my acts_as_versioned plugin is How do you version associations? I have no desire to open that can of worms unless I absolutely need it in a project. Richard Livsey decided he needed this feature, and created acts_as_versioned_association.

class Article < ActiveRecord::Base
  has_many :images
  has_and_belongs_to_many :categories

  acts_as_versioned
  acts_as_versioned_association :images
  acts_as_versioned_association :categories
end