Updated to be more concise:

    def save
      @custom_attributes.merge! 'Name' => name,
                                'CreatedAt' => Time.now.utc.to_s

      current_attributes = attributes.reject do |key,value|
        if value == 'nil'
          @logger.info "Removing attribute set to nil '#{key}'."
          sdb_connect.delete_items 'stacks', name, key => nil
          true
        end
      end

      current_attributes.each_pair {|k,v| @logger.debug "Setting attribute #{k}=#{v}"}

      sdb_connect.put_attributes 'stacks',
                                  name,
                                  current_attributes,
                                 :replace => current_attributes.keys

      @logger.debug "Save to SimpleDB successful."
    end