svc-insert-gists.js

var appendStyle = function(){
  var htmlstr = '<link rel="stylesheet" '+
                'href="https://gist.github.com/stylesheets/gist/embed.css" '+
                'type="text/css" />';
  $('head').append( htmlstr );
}

/*
  look for tags [gist]#######[/gist] and for each one found, insert a
  div with an id attribute that references the gist's id
*/
var processTags = function(){
  $('.post').each(function(i, el){
     var htmlstr = $(el).html();
     var htmlstr2 = htmlstr.replace(/\[gist\](\d{7})\[\/gist\]/g, function(m, gId){
        return '<div id="svc-gist-' + gId + '" ></div>';
     });
     $(el).html( htmlstr2 );
  });
}


// search for all processed tags and load gists
var printGists = function(){

  $('[id^=svc-gist-]').each(function(i, el){ 
    var $target = $(el),
        gistId = $target.attr( 'id' ).substring( 9 ); 

    $.ajax('https://gist.github.com/'+ gistId +'.json', {
              dataType:'jsonp',
              success: function(data){
                $target.append(data.div);
              }
    });
  });
}

appendStyle();
processTags();
printGists();