A WebmasterWorld thread unveils that Yahoo! is also polling select searchers on their PPC ads. Located above the sponsored search results was a poll that read.
How useful were the first 5 results at the top of this page?
1 2 3 4 5 not useful very useful
Yahoo! Research Thank you for your feedback!
We also recently reported that Google polled their users on the AdWords ads. I thought I blogged this in the past either here or at SEW but I couldn't find it.
Forum discussion at WebmasterWorld.