You want to know if the Symantec Brightmail Gateway or Symantec Messaging Gateway products can be monitored with Microsoft's System Center Operations Manager (SCOM) 2007/2012.
Both Symantec's Brightmail Gateway 9.0.2 and the Symantec Messaging Gateway 9.5 cannot be administered with Microsoft's System Center Operations Manager 2007 or 2012. At the time of writing, the upcoming version (10.0) of the Messaging Gateway will also not support this management utility.
As an alternate option, Symantec Protection Center allows a suite of Symantec products to be managed through the one console. Further information on this Symantec product can be found at the URL below.