Madm3n,
First let me mention that this thread is about the What's New Web Part for anyone else who may be wondering what product we are discussing.
Extended Columns are additional columns outside of the base Columns we have already included. Our existing column choices were pulled from the "Base" columns included in every SharePoint List definition. They are simply common across all Lists, less the Attachments column...which we included because we thought is was common enough since it can be enabled for many types of List definitions.
We thought it would be nice to display additional columns that are really part of the "extended" column list for specific List definitions. Columns specific to list types of Tasks, Events, Documents, Pictures, Contacts, etc. However, these "extended" columns are not part of every List definition and will be ignored when selected but are not part of any of the results returned. So if you configured the web part to return Task items across a Site Collection you could now also include some Task specific columns in the Grid view.
Extended Columns as additional options in the Grid Columns dropdown list.
