console_log_subscriber.rb

#
#   ActiveRecord SQL Logging on the Rails Console - revisited/updated
#   -----------------------------------------------------------------
#
# If you're living on the edge ("edge Rails", that is) and would like to
# log all SQL statements executed by ActiveRecord to STDOUT when you're 
# in a Rails console, then the ConsoleLogSubscriber class is for you!
#
# Notes:
#
# (1) integration into ".irbrc" left as an exercise to the reader
# (2) at present (2010-07-16) this is only compatible with edge Rails
# (3) but I expect this will work in the next Rails 3.0 beta or RC release
# (4) this replaces the MultiLogger class: http://gist.github.com/478307
#

module ActiveRecord
  class ConsoleLogSubscriber < ActiveRecord::LogSubscriber
    def initialize
      @logger = Logger.new(STDOUT)
      super
    end
    def sql(event)
      super
    end
    def logger
      @logger
    end
  end
end

ActiveRecord::ConsoleLogSubscriber.attach_to :active_record

ad note (4): this replaces the MultiLogger class

For older versions of Rails 3.0 (ie. "3.0.0.beta4" and before) which don't implement the LogSubscriber class, the MultiLogger class can be used instead:

http://gist.github.com/478307

Lemme know how you get on using these two classes, ActiveSupport::MultiLogger and ActiveRecord::ConsoleLogSubscriber... happy logging! :-)