Google is reported of experimenting "Email Subscription Ads" on search results pages, allowing companies to buy ads that automatically fill in a "Subscribe to newsletter" slot with a given searcher's Google email address during a search.
According to Emailblog reports, it seems Google have expanded its regular AdWords search ads, as the service is now running tests with Honda that includes a direct email subscription option (prefilled apparently if you're a logged in Gmail user) in the search results. Clicking on the "Privacy" button next to the subscription button lets you know that your email will be sent to the advertiser.
A Google representative issued the following statement:
"We're currently running a small experiment of a new ad format that helps users sign up more easily for email subscriptions or other free newsletters. This new ad format contains a box within the ad that displays a user's Google email address (if logged in). If a user chooses to click "Subscribe to newsletter" then the email address is sent to the advertiser directly, which is clearly disclosed within the ad itself."