SMS 2.0 SUS Feature pack
I saw this the other day, and thought it was worth reproducing to make sure that, if you're using MBSA, you can still keep yourself fully up to date...
As documented in KB895660, the MBSA 1.2.1 catalog (MSSecure.XML) that is used to provide security detection and deployment information to MBSA 1.x will be no longer be updated for use with MBSA 1.2.1 after March 31, 2006. The SMS 2.0 Software Update Services Feature Pack and the SMS 2003 Security Update Inventory Tool leverage the MBSA 1.x scan engine and therefore the MSSecure.XML file. To enable customers using SMS 2.0 Software Update Services Feature Pack and the SMS 2003 Security Update Inventory Tool, MSSecure.XML will continue to be updated for use with these SMS tools. The MSSecure.XML file will be updated until SMS 2.0 reaches the end of Extended Support in December 2010.
Newer Microsoft products cannot be supported with either the SMS 2.0 Software Update Services Feature Pack or the SMS 2003 Security Update Inventory Tool due to limitations in the MBSA 1.x scan engine. The Microsoft products not supported by these tools include, but are not limited to: Internet Explorer 7, SQL Server 2005, Windows Vista, Windows Server codename “Longhorn”, and any 64-bit products or platforms.