Easy to circumvent. Spend 5 minutes thinking of how to do it. I suspect you'll think of at least a couple of ways.

The battle against spammers will continue to be cat and mouse game. And when one of your signals gets exposed, of course it will be a target.

There's nothing new here. In fact, I think most spammers already assumed that the toolbar clickthroughs fed into both Bing and Google toolbars. I did.