Support for hierarchical Work Item Queries is one of the flagship features of Team Foundation Server 2010, and TeamCompanion would not be one of the best Team Foundation clients without proper support for it. TeamCompanion 3.0 allows you to organize Work Items into a hierarchy for more convenient viewing. When in the Outlook view pane, hierarchical Work Item Queries are displayed in a standard Outlook table view. Outlook table view is very powerful presentation mechanism, but unfortunately, it does not have a notion of hierarchy natively.
TeamCompanion achieves hierarchical display in table view by indenting specific field values for Work Items...