WordPress.org

Why would I need this plugin?

If you read your WordPress site in Google Reader on your mobile device - and if your site uses images with captions - you've probably noticed how some images look too big for the reader. This plugin fixes that problem by making the photos more responsive, in that they will never be wider than the screen that is viewing them.

What else can I do with this plugin?

You can re-name it and edit it to further alter the way that the default caption shortcode works. Making these changes in a plug-in is better than altering wp-includes/media.php because your changes will still be there next time you automatically update WordPress. Everyone wants to automatically update WordPress. It makes life better.

Read more about RSS Responsive Caption on the author's website here: http://brandonmoeller.com/blog/2011/12/18/rss-responsive-caption/