gistfile1.rb

class SoundWalk < ActiveRecord::Base
  belongs_to :user

  named_scope :from_users, lambda{ |users| {:conditions => ["user_id IN (?)", users.collect{|u| u.id}]} }
end

class User < ActiveRecord::Base
  def friend_soundwalks
    SoundWalk.from_users(self.friends)
  end
end