From http://www.paulund.co.uk/create-wordpress-widget-to-display-twitter-updates

New Twitter Widget

/*
Source Tutorial: http://www.paulund.co.uk/create-wordpress-widget-to-display-twitter-updates

*/

define('MAGPIE_CACHE_ON', 1); //2.7 Cache Bug
define('MAGPIE_CACHE_AGE', 180);
define('MAGPIE_INPUT_ENCODING', 'UTF-8');
define('MAGPIE_OUTPUT_ENCODING', 'UTF-8');

$twitter_options['widget_fields']['title'] = array('label'=>'Title:', 'type'=>'text', 'default'=>'');
$twitter_options['widget_fields']['username'] = array('label'=>'Username:', 'type'=>'text', 'default'=>'');
$twitter_options['widget_fields']['num'] = array('label'=>'Number of links:', 'type'=>'text', 'default'=>'5');
$twitter_options['widget_fields']['update'] = array('label'=>'Show timestamps:', 'type'=>'checkbox', 'default'=>true);
$twitter_options['widget_fields']['hyperlinks'] = array('label'=>'Discover Hyperlinks:', 'type'=>'checkbox', 'default'=>true);
$twitter_options['widget_fields']['twitter_users'] = array('label'=>'Discover @replies:', 'type'=>'checkbox', 'default'=>true);
$twitter_options['widget_fields']['encode_utf8'] = array('label'=>'UTF8 Encode:', 'type'=>'checkbox', 'default'=>false);


$twitter_options['prefix'] = 'twitter';

function twitter_messages($username = '', $num = 5, $update = true, $hyperlinks = true, $twitter_users = true, $encode_utf8 = false) {

	global $twitter_options;
	
	$transName = 'list-tweets'; // Name of value in database.
    $cacheTime = 10; // Time in minutes between updates.
    
    if(false === ($twitterData = get_transient($transName) ) ){
		// Get the tweets from Twitter.
		$json = wp_remote_get("http://api.twitter.com/1/statuses/user_timeline.json?screen_name=$username&count=$num");
		 
		// Get tweets into an array.
		$twitterData = json_decode($json['body'], true);
		
		// Save our new transient.
	    set_transient($transName, $twitterData, 60 * $cacheTime);
	
    } 
		
	echo '<ul class="twitter">';
	
	if ($username == '') {
		echo '<li>';
		echo 'RSS not configured';
		echo '</li>';
	} else {
		
		if(empty($twitterData) || isset($twitterData['error'])){
			echo '<li class="follow_on_twitter">';
			echo '<a href="http://www.twitter.com/'.$username.'" title="Follow Me On Twitter">Follow Me On Twitter</a>';
			echo '</li>';
		} else {
			$i=0;
			
			foreach($twitterData as $item){
					
					$msg = $item['text'];
					$permalink = 'http://twitter.com/#!/'. $username .'/status/'. $item['id_str'];
					if($encode_utf8) $msg = utf8_encode($msg);
					$link = $permalink;
				
					 echo '<li class="twitter-item">';

			          if ($hyperlinks) { 	$msg = hyperlinks($msg); }
			          if ($twitter_users)  { $msg = twitter_users($msg); }
			          								
			          echo $msg;
              
			        if($update) {				
			          $time = strtotime($item['created_at']);
			          
			          if ( ( abs( time() - $time) ) < 86400 )
			            $h_time = sprintf( __('%s ago'), human_time_diff( $time ) );
			          else
			            $h_time = date(__('Y/m/d'), $time);
			
			          echo sprintf( __('%s', 'twitter-for-wordpress'),' <span class="twitter-timestamp"><abbr title="' . date(__('Y/m/d H:i:s'), $time) . '">' . $h_time . '</abbr></span>' );
			         }          
                  
					echo '</li>';
				
					$i++;
					if ( $i >= $num ) break;				
			}
		}
	}
	
	echo '</ul>';
	
}

// Find links and create the hyperlinks
function hyperlinks($text) {
    $text = preg_replace('/\b([a-zA-Z]+:\/\/[\w_.\-]+\.[a-zA-Z]{2,6}[\/\w\-~.?=&#038;%#+$*!]*)\b/i',"<a href=\"$1\" class=\"twitter-link\">$1</a>", $text);
    $text = preg_replace('/\b(?<!:\/\/)(www\.[\w_.\-]+\.[a-zA-Z]{2,6}[\/\w\-~.?=&#038;%#+$*!]*)\b/i',"<a href=\"http://$1\" class=\"twitter-link\">$1</a>", $text);    
    
    // match name@address
    $text = preg_replace("/\b([a-zA-Z][a-zA-Z0-9\_\.\-]*[a-zA-Z]*\@[a-zA-Z][a-zA-Z0-9\_\.\-]*[a-zA-Z]{2,6})\b/i","<a href=\"mailto://$1\" class=\"twitter-link\">$1</a>", $text);
        //mach #trendingtopics. Props to Michael Voigt
    $text = preg_replace('/([\.|\,|\:|\|\|\>|\{|\(]?)#{1}(\w*)([\.|\,|\:|\!|\?|\>|\}|\)]?)\s/i', "$1<a href=\"http://twitter.com/#search?q=$2\" class=\"twitter-link\">#$2</a>$3 ", $text);
    return $text;
}

//Find twitter users
function twitter_users($text) {
       $text = preg_replace('/([\.|\,|\:|\|\|\>|\{|\(]?)@{1}(\w*)([\.|\,|\:|\!|\?|\>|\}|\)]?)\s/i', "$1<a href=\"http://twitter.com/$2\" class=\"twitter-user\">@$2</a>$3 ", $text);
       return $text;
}     

// Create the twitter widget
function widget_twitter_init() {

	if ( !function_exists('register_sidebar_widget') )
		return;
	
		$check_options = get_option('widget_twitter');
		
		  if ($check_options['number']=='') {
		    	$check_options['number'] = 1;
		   	 	update_option('widget_twitter', $check_options);
		  }
  
	function widget_twitter($args, $number = 1) {

		global $twitter_options;
		
		extract($args);

		// Each widget can store its own options. We keep strings here.
		include_once(ABSPATH . WPINC . '/rss.php');
		$options = get_option('widget_twitter');
		
		// fill options with default values if value is not set
		$item = $options[$number];
		foreach($twitter_options['widget_fields'] as $key => $field) {
			if (! isset($item[$key])) {
				$item[$key] = $field['default'];
			}
		}
		

		echo $before_widget . $before_title . '<h3><a href="http://twitter.com/' . $item['username'] . '" class="twitter_title_link">'. $item['title'] . '</a></h3>' . $after_title;
		twitter_messages($item['username'], $item['num'], true, $item['update'], $item['linked'], $item['hyperlinks'], $item['twitter_users'], $item['encode_utf8']);
		echo $after_widget;
				
	}

	//Output the user form
	function widget_twitter_control($number) {
	
		global $twitter_options;

		$options = get_option('widget_twitter');
		if ( isset($_POST['twitter-submit']) ) {

			foreach($twitter_options['widget_fields'] as $key => $field) {
				$options[$number][$key] = $field['default'];
				$field_name = sprintf('%s_%s_%s', $twitter_options['prefix'], $key, $number);

				if ($field['type'] == 'text') {
					$options[$number][$key] = strip_tags(stripslashes($_POST[$field_name]));
				} elseif ($field['type'] == 'checkbox') {
					$options[$number][$key] = isset($_POST[$field_name]);
				}
			}

			update_option('widget_twitter', $options);
		}

		foreach($twitter_options['widget_fields'] as $key => $field) {
			
			$field_name = sprintf('%s_%s_%s', $twitter_options['prefix'], $key, $number);
			$field_checked = '';
			if ($field['type'] == 'text') {
				$field_value = htmlspecialchars($options[$number][$key], ENT_QUOTES);
			} elseif ($field['type'] == 'checkbox') {
				$field_value = 1;
				if (! empty($options[$number][$key])) {
					$field_checked = 'checked="checked"';
				}
			}
			
			printf('<p style="text-align:right;" class="twitter_field"><label for="%s">%s <input id="%s" name="%s" type="%s" value="%s" class="%s" %s /></label></p>',
				$field_name, __($field['label']), $field_name, $field_name, $field['type'], $field_value, $field['type'], $field_checked);
		}

		echo '<input type="hidden" id="twitter-submit" name="twitter-submit" value="1" />';
	}
	
	function widget_twitter_setup() {
		$options = $newoptions = get_option('widget_twitter');
				
		if ( $options != $newoptions ) {
			update_option('widget_twitter', $newoptions);
			widget_twitter_register();
		}
	}
		
	
	function widget_twitter_register() {
		
		$options = get_option('widget_twitter');
		$dims = array('width' => 300, 'height' => 300);
		$class = array('classname' => 'widget_twitter');

		$name = 'Paulund Twitter';
		$id = "paulund_twitter"; // Never never never translate an id
		wp_register_sidebar_widget($id, $name, 'widget_twitter', $class, '');
		wp_register_widget_control($id, $name, 'widget_twitter_control', $dims, '');
		
		add_action('sidebar_admin_setup', 'widget_twitter_setup');
	}

	widget_twitter_register();
}

add_action('widgets_init', 'widget_twitter_init');