It's not unusual to see slightly customized builds of Android rolling out to Nexus devices shortly after the release of a new version. It certainly happened a few times with KitKat, and it looks like Lollipop is on track to do the same. As the rush of factory images and OTAs roll out, AOSP is also receiving commits for the new device-specific builds; and Al Sutton was quick to put out changelogs for each version.
Early yesterday, Google began pushing the complete source code for Android 5.0 Lollipop to AOSP. The code drop was so large that the operation continued to run through the night and into the following day. But, it is finally done. For those that are determined to compile their own build of Android, it's a good time to get your downloads started. However, for the rest of us that are just interested in a more detailed list of changes than what Google has already shown to us, we can turn to the developer changelog generated by Al Sutton of Funky Android.
A couple of days ago, AOSP was graced with a series of freshly created "l-preview" branches and a massive push of brand new code. As we know now, quite a bit of that code push wasn't truly representative of the L developer preview. (Very sneaky, Google.) Most of the truly new updates belonged to GPL-licensed projects, which Google is obligated to release in a timely fashion. The remaining projects with "l-preview" branches were filled with a recent snapshot from the Master branch.
An unexpected treat came zooming out of Google HQ today as Android 4.4.4 OTAs and factory images have started rolling out for Nexus devices. The updates have already been posted to AOSP and Al Sutton quickly followed up with a list of the changes. Since 4.4.3 is only 2 weeks old, and I/O is merely a week away, we had a feeling this was just a security update, and it looks like that's all it is.