A helper class which uses Zend Service to fetch Twitter status' - can be used in any project. See comments for Zend Framework dependencies.

fetch_tweets.php

<?php
/**
 * Twitter status class
 * 
 * Helper Class to fetch status' for a Twitter account via Zend Service.
 * 
 * @package PKLib
 * @subpackage Twitter
 * @author Phil Kershaw
 */
require_once 'Zend/Service/Twitter.php';
require_once 'Zend/Service/Twitter/Exception.php';
require_once 'Zend/Oauth/Token/Access.php';

class PKLib_Twitter_Status
{
	/**
	 * The auth token for connecting to the Twitter API
	 * 
	 * @var string
	 */
	private $_twitter = NULL;
	/**
	 * The results from Twitter
	 *
	 * @var array
	 */
	private $_result = NULL;
	/**
	 * The oauth configuration details
	 * 
	 * @var array
	 */
	private $_config = NULL;
	/**
	 * The path to the file where tweets are cached
	 * 
	 * @var string
	 */
	private $_cacheFilePath = NULL;
	/**
	 * The type of feed to request
	 *
	 * @var string
	 */
	private $_timeline = NULL;
	/**
	 * Available status types
	 * 
	 * @var array
	 */
	private $_status_types = array(	'Home', 'Mentions', 'User',	);
	/**
	 * Constructor
	 * @param  array $config
	 * @param  string $timeline Home|Mentions|User|
	 * @return void
	 */
	public function __construct($config, $timeline)
	{
		$this->_config   = $config;
		$this->_timeline = $timeline;
		
		// set up cache
		$this->_setCacheFile();
	}

	/**
	 * Authenticate with Twitter to obtain an auth token using OAuth
	 * 
	 * @return object PKLib_Twitter_Status
	 */
	public function authenticate()
	{
		$token = new Zend_Oauth_Token_Access();

	    $token->setToken($this->_config['accessToken'])
	    	  ->setTokenSecret($this->_config['accessTokenSecret']);

		$this->_twitter = new Zend_Service_Twitter(
			array(
				'userName'       => $this->_config['userName'],
				'accessToken'    => $token,
				'oauthOptions'   => array(
					'consumerKey'    => $this->_config['key'],
					'consumerSecret' => $this->_config['secret'],
				)
			)
		);

		return $this;
	}
	/**
	 * Fetch the timeline specified in $this->_timeline
	 * 
	 * @param  boolean  $clickableLinks
	 * @param  integer  $limit
	 * @param  boolean $cache
	 *
	 * @throws Zend_Service_Twitter_Exception
	 * 
	 * @return array
	 */
	public function fetch($clickableLinks, $limit, $cache = TRUE)
	{
		try {
			if ((filesize($this->_cacheFilePath) <= 0)
				|| (time() - filemtime($this->_cacheFilePath) > 3600)) { // if cache file is empty or the cache is stale
				// Make sure the type of tweets requested is valid
				if (!in_array($this->_timeline, $this->_status_types)) {
					throw new Zend_Service_Twitter_Exception("Invalid timeline type. Options include: Home, Mentions or User. Please check the functions.php");
				}
				// fetch tweets from twitter
				$timeline  = $this->_timeline;
				$timeline .= 'Timeline';
				$this->_result    = $this->_twitter->statuses->$timeline()->toValue();
				// Make URLs clickable
				if ($clickableLinks) {
					self::_applyUrlEntities($this->_result);
				}
				// cache our all tweets
				if ($cache) {
					$this->_cacheTweets();
				}
				
			} else {
				// fetch our cached tweets
				$this->_result = unserialize(
					file_get_contents($this->_cacheFilePath)
				);
			}			
			// apply the limit to the result set
			if (NULL !== $limit && $limit < 20)  {
				$this->_result = array_slice($this->_result, 0, $limit);
			}
		} catch (Exception $e) {
			error_log($e->getMessage());
		}

		return $this->_result;
	}
	/**
	 * Sets the cache file up
	 *
	 * @return void
	 */
	private function _setCacheFile()
	{
		// Create cache directory
		$path = __DIR__ . '/cache';
		if (!is_dir($path)) {
			$oldumask = umask(0);
            mkdir($path, 0775);
            umask($oldumask);
		}
		// create cache file
        $filename = preg_replace('/[^a-zA-Z0-9_]/', '', $this->_config['userName']) . '_' . $this->_timeline;
        $this->_cacheFilePath = $path . '/' . $filename;
        if (!file_exists($this->_cacheFilePath)) {
        	touch($this->_cacheFilePath);
        }
	}
	/**
	 * Serialises and saves the Tweets to a file
	 * 
	 * @return void
	 */
	private function _cacheTweets()
	{
        if (!file_put_contents($this->_cacheFilePath, serialize($this->_result))) {
        	throw new Zend_Service_Twitter_Exception("Failed to save to Tweets to cache. File path: {$this->_cacheFilePath}");
        }
	}
	/**
	 * Converts URLs into hyperlinks
	 * @param  array $feed
	 * @return void
	 */
	private static function _applyUrlEntities(&$feed)
    {
        if ($feed !== NULL) {
            foreach($feed as &$item) {
                if ($item->entities->urls !== NULL) {
                    $urls    = array_reverse($item->entities->urls);
                    $content = &$item->text;
                    foreach ($urls as $url) {
                        $content = substr_replace($content, '</a>', $url->indices[1], 0);
                        $content = substr_replace($content, '<a href="'.$url->url.'" target="_blank">', $url->indices[0], 0);
                    }
                    unset($content);
                }
            }
            unset($item);
        }
    }
}

The dependencies from Zend Framework 1.12 need for this class:

Crypt/
Crypt.php
Exception.php
Http/
Json/
Json.php
Loader.php
Oauth/
Oauth.php
Rest/
Service/
Service/Abstract.php
Service/Exception.php
Service/Twitter/
Serivce/Twitter.php
Uri/
Uri.php
Validate/
Validate.php