Android 5.1 is only about a month old, but Google is already pushing out a new release to the public AOSP repository. Android 5.1.1, as the name would suggest, consists of a bunch of bugfixes.
If you're wondering exactly what bugfixes, our friends at Android Police have compiled a list of the new commits. It's a small release, with only 34 merged changes. The biggest fixes are for the Nexus 5 and 6 camera failing to launch in some circumstances, along with a few PNG security holes (CVE-2014-9495), which were probably the catalyst for this release. There isn't too much else.
While the fresh code is in AOSP, when phones will get it is another story. The first device to get the update—believe it or not—is the Nexus Player. The Android TV set-top-box already has an image up on Google's Nexus System Image page. For everyone else—um—wait?