Another step has been taken in the march to the release of Android L by Google. A developer preview emulator image has been released for x86 platforms so that developers can get to work in earnest on the 64-bit versions of their apps. By taking advantage of the 64-bit architecture that will be available through Android L, developers will be able to access additional memory space, a larger number of registers, and new instruction sets. For apps built using Java, no changes to code will be needed as they get the benefits automatically.
Android L was announced earlier this year at Google I/O when the inclusion of 64-bit support was noted. Google also released a preview image for developers to start to get a look at the new operating system. Since then, there have been various leaks surrounding the different builds and what may or may not make the final cut. There has also been a lot of conjecture about the new name and the release date.
source: +Android Developers