Yes we do have a Wordpress plugin, available here: http://wordpress.org/extend/plugins/cloudinary-image-management-and-manipulation-in-the-cloud-cdn/. While you don't need to install any image software on your server, you will need to register for a (free) Cloudinary account to use the plugin and start uploading images to the cloud.
If you have existing images, presumably you need to re-upload these, I think