ADPassMon user Cesar Gonzalez sent me a nice note to let me know that Apple engineers suggested using ADPassMon to work around a problem he encountered after deploying FileVault 2. Due to the EFI boot authentication passthrough, his users are no longer notified of the pending password expirations at the login screen. Since ADPassMon runs after the login process, it works whether FileVault 2 is enabled or not.
Adding to ADPassMon’s feature list without any additional work seems like a big win to me. :) Thanks again, Cesar!