Following updates to Chromecast, Google Maps and Google Camera this afternoon, Google has updated Gmail for Android with a new Insert from Drive feature that allows for Google Drive attachments to be inserted into emails directly from Android smartphones and tablets. If the file is not shared with the person you are sending it to, an option will pop up to change the sharing settings.
There is also improved autocomplete suggestions for your Gmail contacts when composing messages, which appear automatically when you start typing in the To, Cc or Bcc fields. The update will be rolling out over the next few days, so be sure to keep an eye on Google Play for the new version.
Gmail for Android was recently updated with full right-to-left support for Arabic, Hebrew and Persian, swipe-from-edge access to the left-side menu, visual updates and more.