Request.Twitter.js

Request.Twitter = new Class({

    Extends: Request.JSONP,

    options: {
        linkify: true,
        url: '/twitter/statuses/user_timeline/{term}.json',
        data: {
            count: 5
        }
    },

    initialize: function(term, options){
        this.parent(options);
        this.options.url = this.options.url.substitute({term: term});
    },

    success: function(data, script){
        if (this.options.linkify) Array.each(data[0], function(tweet){
            tweet.text = this.linkify(tweet.text);
        }, this);

        if (data[0]) this.options.data.since_id = data[0].id; // keep subsequent calls newer

        this.parent(data, script);
    },

    linkify: function(text){
        // modified from TwitterGitter by David Walsh (davidwalsh.name)
        // courtesy of Jeremy Parrish (rrish.org)
        return text.replace(/(https?:\/\/[\w\-:;?&=+.%#\/]+)/gi, '<a href="$1">$1</a>')
                   .replace(/(^|\W)@(\w+)/g, '$1<a href="http://twitter.com/$2">@$2</a>')
                   .replace(/(^|\W)#(\w+)/g, '$1#<a href="http://search.twitter.com/search?q=%23$2">$2</a>');
    }

});

New version, made it MooTools 1.3 compatible (without compatibility).