Initiatives were 'made a top priority after last summer's revelations'
Google has steadily improved the overall security of several of its apps and services, and the latest move is moving to HTTPS and encryption across all of Gmail. Starting today, every single time you send or check your Gmail, the transfer will be made over a secure HTTPS connection. That means that the communication between the device you're using and Google's servers is secure, and nobody will be listening in along the way. Google made this option the default back in 2010, but now there will be no option to browse insecurely when it comes to Gmail.
Further, Google will now encrypt any and all Gmail messages when they're moving between Google servers. That means when you send or receive email with another person using Gmail, your communication will also be completely encrypted. This is something Google says it "made a top priority after last summer’s revelations."
Of course Google can't do a whole lot about email that is sent to email addresses with services other than Google (that's up to you to handle), but it's great to see it doing everything it can for what it can control.
Source: Official Google Blog