I had a question in my head about whether or not Google would use the Facebook "like this" widget in their rankings. So I checked a page on CNN that had the "like this" stuff at the bottom. The code looked like this <span class="connect_widget_connected_text hidden_elem">You and 18 others recommend this.</span> which would seem to be a pretty easy thing for a Googlebot to read.
What would be a good method to test this?