gistfile1.rb

#!/usr/bin/env ruby -wKU

LOG = 'eventcmd.log'
event = ARGV.first
@message = 'Gug.'

def ichat_message
  %Q{set status message to "#{@message}"}
end

def adium_message
  %Q{set status message of every account to "#{@message}"}
end

def applescript
  %Q{
    tell application "System Events"
      if exists process "iChat" then
        tell application "iChat"
          #{ichat_message}
        end tell
      end if
      if exists process "Adium" then
        tell application "Adium"
          #{adium_message}
        end tell
      end if
    end tell
  }
end

def run_applescript
  IO.popen("osascript", "w") { |f| f.puts(applescript) }
end

if event == 'songstart'
  details = {}
  $stdin.each_line do |l|
    details.store(*l.chomp.split('=', 2))
  end
  @message = %Q|now playing \\"#{details['title']}\\" by #{details['artist']}|
  run_applescript
end

Setup:

Open ~/.config/pianobar/config

Add "event_command" with the path to where you save this file.
(The same config where you can store your username and password for logging into pianobar)

Example:
event_command = /Users/username/hacks/adium_pianobar/my_coworkers_rock.rb