WordPress : adding custom columns in the posts list while using a custom post type

custom_post_type_columns

//This filter will allow us to add new columns
add_filter("manage_edit-mycustom_columns", "edit_columns");

//This action will populate the new columns
add_action("manage_posts_custom_column", "custom_columns");

/** 
 * First step : declaring the new columns (in this function, we could also remove the default columns...)
 * @param array $columns
 */
function edit_columns($columns){
	$columns['mycustom_col1'] = 'A neat title';
	$columns['mycustom_col2'] = 'Another neat title';
	
	return $columns;
}

/**
 * Show the columns in the custom post list (in admin)
 * @param string $column
 */
function custom_columns($column){
	global $post;
	
	$custom = get_post_custom_values($column,$post->ID);
	
	switch($column){
		case 'mycustom_col1':
			//Here we can "play" with our data ... and then echo it
			echo $custom[0];
		break;
	
		default:
			echo $custom[0];
		break;
	}
}