Editors' Note, November 3, 2014: The link to the Gmail 5.0 APK has been updated to point to a newer version.
The newest version of the Gmail app features auto-updating email threads, the ability to add accounts from other email providers and Exchange support. This means that you'll no longer need to use two separate apps to access your email.
Want to try it out? Luckily, Android Police has just acquired the Android package (APK) of Gmail 5.0, and has shared it on its APK Mirror website. This means you can get a copy of it now and don't have to wait for the update through Google Play.
The APK is signed by Google, which guarantees its authenticity.
Here's how to get started:
Grab a copy of Gmail 5.0 from APKMirror. Once the download finishes, tap the notification and then press the Install button. This APK is signed and authentic, meaning that it will upgrade the version of Gmail you currently have installed.
If you add multiple accounts, you can switch between them by opening the left-hand slide-out menu and swiping across your profile banner. You can also tap the small arrow and choose an account from the list.
If you want to add Exchange support to your Gmail client, you'll need to download an additional APK.
If you installed Gmail 5.0 first, you may need to force stop your Gmail app in order for it to recognize the Exchange capabilities. This can be done by going to Settings > Applications > Gmail > Force stop.
After this, you'll be able to add your Exchange accounts just like the others above.
This new version is very similar to the last, save for the Material design and under-the-hood account support.