Yay! You can now root Android 5.0 Lollipop on all Nexus devices!
A word of warning, though – you definitely want to know what you're doing for this one, as the only way to currently obtain root is by booting a fastboot image. Keep in mind that your Nexus device might also need to have its bootloader unlocked before you initiate the process. Granted, these are not overly-complicated procedures, but if the above terms mean nothing to you, then you might want to abstain for now and play it safe. Refer to the resources available below to learn more about the process if you're comfortable modding your device.
By the way: Yay!
Things that are NOT allowed: