Basic Twitter object, demo at the bottom (require jQuery here but could also write your own Ajax function). This should work w/ all Twitter APIs which do not require authentification.

gistfile1.js

// Extending the JS Object (not really advised in theory but we really need this to know an associative array size)
Object.prototype.size = function () {
  var len = this.length ? --this.length : -1;
    for (var k in this)
      len++;
  return len;
};

// Twitter class
function Twitter() {
  this.base_url = 'http://api.twitter.com';
  this.version = 1;
  
  Twitter.prototype.api = function(settings) {
    var api_uri = this.base_url + '/' + this.version + '/' + settings.api + '/' + settings.method + '.' + settings.format;
    
    if (settings.params.size()) {
      api_uri += '?';
      for (var param in settings.params) {
        if (settings.params[param] == null || settings.params[param] == false || settings.param == 'size')
          continue;
          
        api_uri += param + '=' + settings.params[param] + '&';
      }
    }
    
    return api_uri + 'callback=?';
  };
  
  Twitter.prototype.htmlize_tweet = function(tweet) {
    // replace url w/ links
    tweet = tweet.replace(/(\b(https?|ftp|file):\/\/[-A-Z0-9+&@#\/%?=~_|!:,.;]*[-A-Z0-9+&@#\/%=~_|])/gi, '<a href="$&" target="_blank">$&</a>');
    // replace hashtags w/ links
    tweet = tweet.replace(/#(\w+)/g, '<a href="http://search.twitter.com/search?q=%23$1" target="_blank">#$1</a>');
    // replace @username w/ links
    tweet = tweet.replace(/@(\w+)/g, '<a href="http://twitter.com/$1" target="_blank">@$1</a>');
    // return HTMLized tweet
    return tweet;
  };
};