thumbnail support on twentyten

// Add theme support for post thumbnails add_theme_support(‘post-thumbnails’); add_image_size( ‘custom_thumb’, 150, 150, true);   // Add thumbnail to excerpt add_filter( ‘the_excerpt’, ‘excerpt_thumbnail’ ); function excerpt_thumbnail($excerpt){ if(is_single()) return $excerpt; global $post; if ( has_post_thumbnail() ) { $img .= ”.get_the_post_thumbnail($post->ID, ‘custom_thumb’).”; } else { $img = ”; } return $img.$excerpt; }