When I'm searching for something, my behavior is usually:
Google search term
Open the top couple results in a new tab
Check each tab, to see if they contain the information I was looking for
If tab is not useful, or more information is required, check next tab.
If information is satisfied, close window (all tabs, including search)
If no tabs remain, and still need more information, return to search page and check next results.
That process has been in place since I upgraded to firefox from ie6 all those years ago. Before then, my search process consisted of: Google search term
Check first result link
If information has been satisfied, close window.
If more information is needed, go BACK, check next link.
My point is, Google search is a launching platform. I typically only go back to the results page when the result didn't provide the information I was looking for. In order to use the feature, I'd have to alter my process to include a return trip to the results page, find the link that led to the page I found interesting and then +1 it. No way this is gonna happen. Ever.The only way I see this feature being implemented in a workable solution is as a browser addon--so that when I'm on a page that I find particularly awesome [whether I found it via search results or by following some page link] I can click on the +1 toolbar button.
Such an implementation would I think would also enhance the result set of affected links. In it's current implementation I'll only find plus one's when I just happen to be searching for the same or similar thing as some one from my social circle. Where as as a browser extension I'll find plus ones for any page that any one in my social circle has visited and found interesting regardless of if they ever issued a query for that subject matter.