Google has sent out a note to developers, which has virtually leaked the release date for Android 5.0 Lollipop.
The Company has sent out the 5.0 SDK to developers, as you can see from the above pic, where it also says that the OS will be released on November 3rd.
This also happens to be the day, when the Nexus 6 smartphone, and the Nexus 9 tablet are going to be officially made available.
The Lollipop update will be rolled out via an OTA update, to the Nexus 7 WiFi, and the Nexus 10 tablets on November 3rd, with the Nexus 4, 5, and Nexus 7 LTE, to receive it later in the same month.
It is rumored that Google is ironing out issues with Mobile Network Connectivity, and hence the delay in rolling out the updates for said devices.