Just found this - a leaked copy of the Gmail application for the NEXT version of Android 4.2. Not Jellybean, the next, K-letter named version. What are they going to use for this one? Every android version has an incremental version number, and also an incremental first letter on name. It is time for the K now. KrispyKremeDelight? See the goodness in action - besides lateral swipe to archive a message, it has improvements on handling attachments, etc. Installation is possible on devices running Android 4.x.x versions. Head on to Android Police HERE, and READ the install guide, get the apk from their download links. You probably need Root access to replace your current Gmail, as it's a System app. A good thread at XDA Developers also covers this, and shows a couple of install methods.