Android L is a major change from previous Android builds, in that they are not only are they waiting months after announcing it before they ship the final version, they are also introducing a developer’s preview. Yesterday we were promised that the preview would arrive sometime on June 26th, and now the moment we’ve been waiting for is here! The Android L factory images have touched down for the Nexus 5 and Nexus 7 (2013) Wi-Fi, and you can get them now by visiting Google’s developer page.
Before you start downloading, keep in mind that this is a PREVIEW, and that means there are bugs and other issues present. There are also likely missing features that will end up in the final L release this fall. Bottom-line, proceed at your own risk.
[Source: Android Authority]