Contact Form 7 Response Colorbox Popup is a WordPress plugin by dudaster makes Contact Form 7 response message when you push submit in a popup colorbox window.
You need Lightbox Plus Colorbox and Contact Form 7 installed.
This plugin does not put an entire contact form inside a colorbox popup but just the response message when you click the Submit Button.
Download: http://wordpress.org/plugins/contact-form-7-response-colorbox-popup/