All the new images have the same build number (LMY48I), which is what Sprint listed as the Stagefright fix for the Nexus 5 and 6 this morning. There might be other things included in this version, so we're digging around and will update if we find anything.
The seven devices with new factory images are the Nexus 6, Nexus 9 (WiFi and LTE), Nexus 5, 2013 Nexus 7 (WiFi), Nexus 10, and Nexus 4. Just boot into the bootloader and execute the included batch file to flash via ADB. Grab them from here : Factory Images