It's not nearly as good as it used to be but still sends some traffic. If your setup is automated it would be a better bet.
I sell physical products and yes, it works for me. I also take Google Checkout, so I have the little Google Checkout badge next to my products. I think many shoppers specifically look for that badge, because it seems like sales have increased since it was implemented. I wouldn't depend on it solely, as it isn't that great, but every little bit helps.