When users are browsing the category hierarchy for a workspace, documents from other SharePoint Portal Server workspaces can be displayed if the category hierarchy is the same.
To display documents from other SharePoint Portal server workspaces, you must create an identical category hierarchy on each workspace, and then have one workspace index the other.
For example, if a workspace named WorkspaceA contains the following category hierarchy
Sales
Sales:East
Sales:West
Sales:North
Sales:South
Sales:West:Northwest
and you want a sales document in a workspace named WorkspaceB to be displayed when users browse to the Sales:West category on WorkspaceA, you need to create categories on WorkspaceB called Sales and Sales:West, and then assign the document to the Sales:West category. Then create a content source on WorkspaceA to index WorkspaceB, and the document is displayed in WorkspaceA's hierarchy.
You must create the category with the same full hierarchy. For example, if you want a document in WorkspaceB to display in the Sales:West category in WorkspaceA, you must create a top-level Sales category, with a West sub-category in WorkspaceB. If you create only a top-level West category, the document is not displayed.