This script should return the date and time of a logged in OS X user's Active Directory password expiration. Please test and let me know if you get an accurate value.

get_ad_pass_expiration.sh

#!/bin/bash
USER=$(/usr/bin/python -c \
      'from SystemConfiguration import SCDynamicStoreCopyConsoleUser;\
       print SCDynamicStoreCopyConsoleUser(None, None, None)[0]')
xWin=$(/usr/bin/dscl localhost read /Search/Users/$USER \
       msDS-UserPasswordExpiryTimeComputed 2>/dev/null |\
       /usr/bin/awk '/dsAttrTypeNative/{print $NF}')
xUnix=$(echo "($xWin/10000000)-11644473600" | bc)
/bin/date -r $xUnix

1. I added:

USER=`python -c 'from SystemConfiguration import SCDynamicStoreCopyConsoleUser; import sys; username = (SCDynamicStoreCopyConsoleUser(None, None, None) or [None])[0]; username = [username,""][username in [u"loginwindow", None, u""]]; sys.stdout.write(username + "\n");'`

to get my username. When Run I get:
I get a error of:
(standard_in) 1: parse error
date: option requires an argument -- r
when I echo out both variables, they come back empty.

1. OS: OSX 10.10.4
2. DC: Win 2K8

1. Is the output of the script accurate?
   Yes
2. What version of OS X are you running?
   10.10.4
3. What version if Windows is/are your DCs running?
   2K12

I used the same method as rderewianko to define USER.

❯ echo $expireDateWin
130849187704716095
❯ echo $expireDateUnix
1440445170
❯ date -r $expireDateUnix
Mon Aug 24 15:39:30 EDT 2015

• Is the output of the script accurate? Yes (well 28 seconds off of ADPassMon 2.10.1).
• What version of OS X are you running? 10.9.5
• What version if Windows is/are your DCs running? 2K8