With the new Catalog, you can search for updates available through the Microsoft Update service and download them to your machine (regardless of whether the update is applicable to your machine).

You can also import updates from the Catalog directly into WSUS 3.0, System Center Essentials 2007, or System Center Configuration Manager 2007….

Additional features of the new catalog include Full-text search, RSS, Download with BITS, Shopping basket for multiple update selection.

More info at the source HERE.