Honeypot , to catch spam bots

This is a wordpress plugin ( http://wordpress.org/extend/plugins/contact-form-7-honeypot/ ) , it adds a hidden form input field , in your contact form , so the spam bots will fill it automatically , but the form submission will fail if you fill it .

Usually normal users will not see this empty hidden field , and so their submission will be correct .

Surely , the same concept can be applied in any form not only wordpress forms.
I have first read about this in Lornajane blog ( http://www.lornajane.net/posts/2012/wordpress-contact-form-7-without-captcha ) .