Today, it appears the OTAs are beginning to hit the masses, but be warned, all these do is patch Stagefright. They contain no other fixes of any kind, so if there's some problem with your device you're hoping to have solved with this update, it's not going to happen. That said, we've got links to some of the OTAs below, and will have others as they become available:
In case you're wondering why the Nexus 7 2012 isn't listed here, it appears that Google has stopped software updates for that device. Released in July 2012, it's now past the three-year window for security updates that Google recently announced. As such, factory images were not released for that device, and it's unlikely we'll see an OTA either.