"[ots-dev] Stamp/Beacon Trees for Secure, Precise, Trusted Timestamping and Clock Synchronization" - https://lists.opentimestamps.org/pipermail/ots-dev/2021-January/000106.html

tl;dr: My new merkle tree construction combines the precision of NTP, and the security of Roughtime. And unlike either, it can be scaled arbitrarily with untrusted servers.

Added to the #OpenTimestamps protocol, it'd allow one service to provide both high accuracy, trusted time, and trustless, low-accuracy, Bitcoin timestamps. A one-stop-shop for all your timing needs.