Enterprising folks over at XDA published a Nexus 5 Android L system dump, making it possible to get at least some parts of the L experience on your current device.
Google released factory Android L images for the Nexus 5 and the Nexus 7 (2013)
yesterday, letting developers and enthusiasts get a taste of the L release, due this fall. But not everyone has a Nexus 5 or Nexus 7, and not everyone is willing to use a preview version of Android as a daily driver.
Thanks to the Nexus 5 system dump, you can try out some of the apps, fonts, and wallpapers available on L release on your current device.
One of the apps that’s been fully reworked to take advantage of the new Material Design paradigm is the stock Keyboard app. With a bit of tinkering, you can install it on a rooted device running Android 4.4 or higher. The app was supposedly tested on devices like the Galaxy S5, LG G2, HTC M8 and more. You will need to uninstall Google Keyboard from your device first, and further instructions are available on this XDA thread.
And, from this thread, you can download Play Services 5, other apps, default wallpapers, system fonts (including redesigned Roboto), ringtone and alarms, and the swanky new Android boot animation. Not all packages are flashable, but tinkerers may still find uses for them. Enjoy!