This is thanks to XDA Recognized Developer and Contributer BeansTown106 (via XDA Developers) who managed to get his hands on the APK and uploaded it online. If you’ve installed APKs before, then the process should be pretty straightforward as it is the same as installing other APKs. The download link can be found here, although as is usually the case with all unofficial downloads, you should probably make sure you know what you’re doing before you proceed.
If anything this leak pretty much confirms what we covered yesterday, which is that the dedicated app drawer button is gone, and in its place there is a swipe up function that will pull up all your apps. Google’s search bar widget has also been replaced by a tab that pulls out from the left. We can’t say for sure if this launcher is the final launcher that Google plans on including its Nexus phones, but so far it does look like what we have been told.