gistfile1.php

<?php
	
	/**
	 * This filter makes it easy to use the same WordPress theme and resources
	 * accross multiple WordPress MU blogs.
	 */
	function my_global_template_url( $url ) {
		
		// Uncomment this to use Amazon S3
		// return 'http://mybucket.s3.amazonaws.com';
		
                // Will always use the main blog path to ease browser caching. For example,
                // it would use `http://mydomain.com/wp-content/themes/mytheme`
                // even if the current blog is `http://mydomain.com/myblog/`.
                // (even if `http://mydomain.com/myblog/wp-content/themes/mytheme` would work)
		global $current_blog;
		return str_replace( $current_blog->path, '/', $url );

	}
	add_filter('template_directory_uri', 'my_global_template_url');