It's given developers a chance to play with some of the upcoming changes to Android that Google announced at its I/O conference last month, including a look at Android L's "material design" principles for its user interface; Project Volta, Google's plan to improve battery life; and various other tweaks to the interface.
But while Google published Android L source code for the Nexus 4, Nexus 5, Nexus 7, and Nexus 10, the developer preview firmware was only available for the Nexus 5 and Nexus 7 wi-fi 2013 edition devices.
However, developers on the XDA forums have bridged the Nexus 4 and Nexus 7 gap, giving users on the two devices the chance to play with the new but currently incomplete OS.
While the first and second builds of the preview Android L for the Nexus 4 suffered from wi-fi issues and other bugs, a new update called 'Beta 3 Preview' is thought to have addressed many of the problems. Other issues listed on the project's GitHub bug tracker page that are being worked on include problems with the camera, lock screen, LTE, and tethering issues.
Anyone keen to install Android L will find that many apps are broken in the OS — there's a live list being updated here.
A port for the Nexus 7 2012 is also available, however, as the developer that built it notes, it's "fairly useless" since many critical features don't work.
While it's still too early to say which devices will get Android L, the release of source code for all current Nexus devices suggests they will get the update when it arrives this autumn.