The new Privacy & Terms can be read from: https://www.google.co.id/intl/en/policies/terms/archive/20131111-20140414/
This is the statement: Our automated systems analyze your content (including emails) to provide you personally relevant product features, such as customized search results, tailored advertising, and spam and malware detection. This analysis occurs as the content is sent, received, and when it is stored.
What other tech giants policy? Read http://bgr.com/2014/03/24/gmail-email-snooping-terms-apple/
So be very careful, there's no such thing as privacy.