Tag Ownership

Tags can have owners:

class User < ActiveRecord::Base
  acts_as_tagger
end

class Photo < ActiveRecord::Base
  acts_as_taggable_on :locations
end

@some_user.tag(@some_photo, :with => "paris, normandy", :on => :locations)
@some_user.owned_taggings
@some_user.owned_tags
Photo.tagged_with("paris", :on => :locations, :owned_by => @some_user)
@some_photo.locations_from(@some_user) # => ["paris", "normandy"]
@some_photo.owner_tags_on(@some_user, :locations) # => [#<ActsAsTaggableOn::Tag id: 1, name: "paris">...]
@some_photo.owner_tags_on(nil, :locations) # => Ownerships equivalent to saying @some_photo.locations
@some_user.tag(@some_photo, :with => "paris, normandy", :on => :locations, :skip_save => true) #won't save @some_photo object