Is ther a Posts in same Category Widget

I don’t know if there exists such a thing, but here is the code to do it:

<?php

/*
 Plugin Name: Post Category Widget
 Version: 1.0
 Description: Widget to show a list of posts from the current post's category.
 Author: Austin Matzko
 Author URI: http://www.ilfilosofo.com/
 */

function current_category_widget_list($args) {
	if ( have_posts() && ( is_single() || is_category() ) ) :
		the_post();
		$post_id = get_the_ID();
		$post_id = intval($post_id);
		rewind_posts();
		wp_reset_query();
		extract($args);
		$cats = (array) wp_get_post_categories($post_id);
		$cat_id = ( is_category() ) ? intval(get_query_var('cat')) : intval(array_shift($cats));
		$r = new WP_Query("cat=$cat_id");
		if ($r->have_posts()) :
			echo $before_widget . $before_title . sprintf('Recent Posts in "%s"', get_cat_name($cat_id)) . $after_title; ?>
				<ul>
				<?php  while ($r->have_posts()) : $r->the_post(); ?>
				<li><a href="<?php the_permalink() ?>"><?php if ( get_the_title() ) the_title(); else the_ID(); ?> </a></li>
				<?php endwhile; ?>
				</ul>
			<?php echo $after_widget;
			rewind_posts();
			wp_reset_query();
		endif;
	endif;
}

function current_category_widget_list_init() {
	wp_register_sidebar_widget( 'current-post-category-list', 'Current Category List', 'current_category_widget_list');
}

add_action('init', 'current_category_widget_list_init');