I recevied some feedback that I didn't include information about the ITCU when I did my post about the SMS 2003 scan tools.
So, here you go:
Inventory Tool for Custom Updates (ITCU): This scan tool ships as one of the features of SMS 2003 R2. It operates similarly to the other scan tools in that it has a scan component and a catalog of metadata that is used to detect applicability, installation and "IsInstalled" rules. The big difference is that the catalog is not sync'd on a schedule and must be manually done via the Custom Updates Publishing Tool (CUPT).
The publishing tool is where the real magic and power of this feature come into play as it enables customers, ISV's, OEM's, etc. to generate thier own catalogs for LOB or 3rd party updates. There are already a few ISV's that have created catalogs, you can find them here: http://www.microsoft.com/smserver/partners/itcucat.mspx
System Center Updates Publisher (SCUP): This is the next generation of the publishing tool, and primarily designed for use with System Center Configuration Manager and System Center Essentials. You can find more information about SCUP in Jason Lewis's blog here: