Thanks to Andrew Boie of Intel for posting this information to the Android-IA list on 01.org:
https://lists.01.org/pipermail/android-ia/2015-April/000894.html
Andrew points to the new Google Verified Boot spec, the current public version of which is here:
https://source.android.com/devices/tech/security/verifiedboot/verified-boot.html
Andrew gave a talk about this at the Android Builder’s Summit:
Click to access ABS%20Lollipop%20MR1%20Verified%20Boot.pdf