Prevent comment SPAM with jQuery draggables/droppables

Hey people,
I came up with an idea to help fight comment spam, the stuff most of
us hate. It's just an idea, maybe it won't even work. But take a look
and tell me what you think, or tell me why this won't work. It's
basically a captcha that requires user action with draggables/
droppables.
http://www.strezlab.com/dropcomment.html
I'd love to hear what you guys think!
Gavin