A gist that shows how I'm embedding gists into Propane. Probably crappy but at least it feels a bit meta...

gistfile1.js

if (displayExpandedGists) {

  Campfire.GistExpander = Class.create({
    initialize: function(chat) {
      this.chat = chat;
      var messages = this.chat.transcript.messages;
      for (var i = 0; i < messages.length; i++) {
        this.detectGistURL(messages[i]);
      }
    },

    detectGistURL: function(message) {
      /* we are going to use the messageID to uniquely identify our requestJSON request
         so we don't check pending messages */
      if (!message.pending() && message.kind === 'text') {
        var links = message.bodyElement().select('a:not(image)');
        if (links.length != 1) {
          return;
        }
        var href = links[0].getAttribute('href');
        var match = href.match(/^https:\/\/gist.github.com\/([0-9]+)\/?$/);
        if (!match) return;
        href = 'https://api.github.com/gists/' + match[1];
        window.propane.requestJSON(message.id(), href, 'window.chat.gistexpander', 'onEmbedDataLoaded', 'onEmbedDataFailed');
      }
    },

    onEmbedDataLoaded: function(messageID, data) {
      var message = window.chat.transcript.getMessageById(messageID);
      if (!message) return;
      var payload = '';

      var description = data['description'];
      if (description) {
        payload += '<strong>Gist:</strong> ' + description + '<br />';
      }

      var files = data['files'];
      if (files) {
        payload += '<strong>Files:</strong> ';

        for (var fileKey in files) {
          var file = files[fileKey];
          payload += '<a target="_blank" href="' + file['raw_url'] + '">' + fileKey + '</a> ';
        }
      }

      message.resize((function() {
        message.bodyCell.insert({bottom: '<div style="width:100%; margin-top:5px; padding-top: 5px; border-top:1px dotted #ccc;">' + payload + '</div>'});
      }).bind(this));
    },

    onEmbedDataFailed: function(messageID) {
      /* No cleanup required, we only alter the HTML after we get back a succesful load from the data */
    },

    onMessagesInsertedBeforeDisplay: function(messages) {
      for (var i = 0; i < messages.length; i++) {
        this.detectGistURL(messages[i]);
      }
    },

    onMessageAccepted: function(message, messageID) {
      this.detectGistURL(message);
    }
  });

  Campfire.Responders.push("GistExpander");
  window.chat.installPropaneResponder("GistExpander", "gistexpander");
}