Today, Google quietly announced a new version of Android in a small blog post. The new version, Android 5.1, is still called Lollipop, but it will come with a few new features including Device Protection, and HD voice (where your device and network supports it).
Android 5.1 will also support multiple SIMs on devices that contain multiple SIM slots (presumably carriers and manufacturers have had to add this support where applicable on top of Android until now).
Device Protection will allow a user to remotely lock their device if it gets lost or stolen. This will prevent your phone from being used until you log in with your Google account. This protection even remains in place if the person who takes your phone performs a factory reset. These are just a few of the new features that will come in Android 5.1, though Google hasn't released a full changelog. The update is rolling out to certain Nexus devices today — presumably it will still take a few weeks or months to get to most other devices.
Android 5.1: Unwrapping a new Lollipop update [Official Android Blog]