You can categorize documents in your document library by listing it under various areas under the portal using the “Submit to Portal” option. This adds the document as a listing to “Portal Listing” in the “Area”. Then you go to the specific area and add the Grouped Listing WebPart, you are shown the Portal Listing contents. A link is provided to the document in the document library.

Does anyone know how to programmatically manipulate the Portal Listing?

I.e. The portal Listing contains only a link to the document. I want to let us say access the creation date of the document and decide whether to display it or not.

I have created a webpart which displays will get the output of the Portal Listing (by using the ListingSummary webpart as a child control). But I am not able to find a way to access the Meta data of the actual document.