Android Lollipop starts to rollout to Nexus devices
Google has begun to rollout Android Lollipop its family of Nexus devices, according to the official Nexus Google Plus page. Google has said that the update will be available on most Nexus devices in the coming weeks. The updates will be made available over-the-air, and won't wipe a user's device.
Google has almost made Lollipop "factory images" available for the Nexus 5, Nexus 10, and 2012 and 2013 WiFi-only Nexus 7. While these will install the update, they will also completely wipe the device in question.
Lollipop factory images can be downloaded here. Ars Technica has a comprehensive guide to flashing a Nexus device with a factory image, but CyberShack advises that this process should only be undertaken by advanced users.