Google allows you to export your data through their "Google Takeout" service. This includes your contacts and circles, unlike facebook, who is now pushing harder than ever to keep your contacts in Facebook.
"Mass exportation of email is not standard on most social networks — when a user friends someone they don’t then expect that person to be easily able to send that contact information to a third party along with hundreds of other addresses with just one click. In order to protect user privacy, we now exclude email addresses from the CSV export file."
http://techcrunch.com/2009/10/26/orkut-slows-hemorraging-to-...
They're right. Programmatic export of friends' email addresses is too ripe for abuse in the world we live in.