vhf

You could simply modify your query to get recent posts by currently logged in user :

<?php

if( is_user_logged_in() ) :
	global $current_user;
	get_currentuserinfo();

	$querystr = "
		SELECT comment_ID, comment_post_ID, post_title, comment_content
		FROM $wpdb->comments, $wpdb->posts
		WHERE user_id = $current_user->ID
		AND comment_post_id = ID
		AND comment_approved = 1
		ORDER BY comment_ID DESC
	 ";

	$comments_array = $wpdb->get_results($querystr, OBJECT);

	if( $comments_array ): ?>
<h2>Your Recent Posts</h2>
<ul>
<?php
		foreach ( $comments_array as $comment ):
			setup_postdata( $comment );
			echo "<li><a href='". get_bloginfo( 'url' ) ."/?p=".$comment->comment_post_ID."'>Comment on ". $comment->post_title. "</a><br />". $comment->comment_content . "</li>";
		endforeach; ?>
</ul><?php
	endif;
endif;
?>