To the disappointment of the Nexus 4 and Nexus 7 (2012) owners, Google only released the Android L developer preview for the Nexus 5 and Nexus 7 (2013).
However, with the source code and the SDK being released by Google, it was just a matter of time before some developers managed to bring a partially working port of Android L to these devices.
Now, thanks to the hard work of some developers over at XDA forums, both devices have received a working Android L Developer Preview port. While the Nexus 7 (2012) has received an SDK port, the Nexus 4 build is a direct port of the Android L build for the Nexus 5.
However, both these builds are far from being stable enough to be used as a daily driver as many core functionalities are completely broken. Nevertheless, they are still good enough to give you a taste of Android L before Google releases the final build for the Nexus 4, and hopefully for the Nexus 7 (2012), later this year.
Installing the build is as simple as flashing any other custom ROM, which in turn means an unlocked bootloader with a custom recovery installed is a necessity.
Head over to the links below to download the builds for your respective Nexus devices.