While I do not see any official announcement, it appears that an upgrade to Webmail is starting to take place over the last week as shown in the about screen.  (I can't seem to find a method to attach a screenshot to a post)  What's interesting is that is not updated for every account I have seen.

There are small visual changes like the icon in the browser tabs, I am curious if there will be more of an announcement and potentially added features.  (For security reasons, one good example is 2-factor authentication or web drive)