Google #Recaptcha (via http://gstatic.com) updated their js so it now does a triangle request/cookie sync w/ http://google.com.
For now on Google's Recaptcha service can be classified as an *#Advertising Network* - and no longer as a Service Provider.
Fun Fact: #Google Policies admits Re-Captcha's http://gstatic.com is specifically used in Ads products @ https://policies.google.com/technologies/types?hl=en-US
"We use various domains to set cookies used in our adv products, including the following domains..."