Can be found here for 12.1 (first link):
http://www.symantec.com/connect/downloads/new-sep-content-distribution-monitor-gup-health-checking
Direct download:
https://www-secure.symantec.com/connect/sites/default/files/SEPM%20Content%20Dist%20Monitor%20-%20BETA%20v1.3.zip
Also, there is a KB article here:
SEP Content Distribution Monitor / GUP monitoring tool.
http://www.symantec.com/docs/TECH156558
Hasn't been updated in some time but still works. I use it to make sure my GUPs are online.