June's Android security updates started rolling out earlier this week, but you could still be waiting for them if they're going out in batches. Those of you who are too impatient can get the full factory image and flash it or download the smaller OTA files linked here and sideload them. Cody already posted the detailed changelog if you want to read about all the changes, but if you're just interested in the links, here they are.
Nexus 6P
Nexus 5X
Nexus 6
Nexus 5
Nexus Player
Nexus 9 WiFi
Nexus 9 (LTE)
Nexus 7 2013 WiFi
Nexus 7 2013 (LTE)
Nexus 10 (Lollipop)
No longer supported, probably, as discussed earlier.