all_s3_objects.rb

# by default you only get 1000 objects at a time
# so you have to roll your own cursor

S3.connect!

objects = []
last_key = nil
begin
  new_objects = AWS::S3::Bucket.objects(bucket_name, :marker => last_key)
  objects    += new_objects
  last_key    = objects.last.key
end while new_objects.size > 0

# you can easily define the above as an all_objects method on AWS::S3::Bucket