Released to address several issues with battery life, stability, performance, etc. Android 5.0.1 has been released to AOSP and is also available as downloadable factory images for several Nexus devices. Included in the 5.0.1 factory image distribution today is the Nexus 9 (WiFi), the 2013 Nexus 7, and the Nexus 10, which you can grab from here.
The new release is supposed to be faster, better, stronger, much like a beloved Daft Punk song, but most of what I can find involves fixes for Android Wear issues. The location of a detailed changelog eludes me at the moment.
5.0.1 should not be a monumental obstacle for most developers, so those worrying that their manufacturer promised 90-day window for Android L would now reset shouldn’t worry. Those on pure AOSP ROMs can probably expect to read their ROM maintainer cursing up a storm today also.
If you’re a Nexus owner, let us know if there’s anything particularly amazing with the new build. My guess is it’s mostly under the hood and not feature extensions.