gistfile1.js

plugin.EmoticonPlus = function(matcher, image) {
    this.matcher = matcher;
    this.image = image;

    this.getImage = function() {
        var img = ['<img src="', image, '" />'];
        return img.join('');
    }
}

plugin.emoticons = [
    new plugin.EmoticonPlus (/\(poolparty\)/, "http://factoryjoe.s3.amazonaws.com/emoticons/emoticon-0182-poolparty.gif")
];

plugin.onMessageInsertion = function(talkerEvent){
  // to replace pasted text as well, change .find(".line") to .find(".line,pre")
  var element = Talker.getLastRow().find(".line");
  _.each(plugin.emoticons, function(emoticon) {
	element.replace(emoticon.matcher, emoticon.getImage());
  });
}