Sending an email is akin to mailing a postcard. Everything written in it can easily be read, copied or analyzed by any one of the email transfer points. It is this simple fact that motivates security advocates to push for email encryption. The main obstacle to mass adoption of email encryption is the complexity. It requires installation and configuration of special software. It requires the purchase or generation of you private/public keys.
Google wants to change all of that and has released an alpha Chrome plug-in called End-to-End (link). End-to-End will provide an additional layer of security over and above what your existing email prover already makes available. The plug-in means all of the complexities of encryption are hidden from the user which should help at-risk but less technically savvy users happy (journalists, human rights workers, whistleblowers, etc).
Google is clear that this is currently an alpha release for technically proficient users only and is not meant for general use yet. They want the community to review the open source plug-in and provide security recommendations to strengthen and improve the tool.
I haven't reviewed the tool just yet but am really happy google is taking the first step in making email more secure and accessible. Once this plug-in is ready for general consumption, I'll let you know.