According to different Nexus 5 users (spotted on Reddit) Google now offers one free screen replacement of Nexus 5. The new policy offers one time replacement of shattered Nexus displays or any damaged caused by water. With the new unannounced policy, Google will offer you a Refurbished or new Nexus 5 device.
Once the order has been made, Google will charge you for the device, but will refund the money when it receives the broken device. This is done for security reasons. This is the first time Google offers this type of replacement, previously you could get only a replacement if you had a hardware defect.
Your Nexus device is only eligible for replacement if it was purchased in the US and via the Google Play Store. Google is soon expected to reveal a new Nexus device which is rumored to be called Nexus X