Rosario is next release of TFS after upcoming Orcas release. You can read a lot about Rosario from Brian's blog. CTP is available to try these features. This post briefly lists UI featuers in links control.
By default, the new links control now shows the links grouped by link type. See the screenshot above. The child links are grouped and each linktype group can be expanded/collapsed. Many customers asked "can I show state & assigned-to in links control?". Now admins can add any column to the links control. Also multiple linkscontrols can be added in a form with each control showing different linktypes. Each linkscontrol can be customized with specific link types, for example, one linkscontrol with parent/child links, another one with related and another with all other links. Check out Gregg's post here on how to filter the link types and how to give name for each control. His post does not give example for adding custom columns, see bolded lines below for adding custom columns.
<Control Type="LinksControl" Name="UniqueName">
<WorkItemLinkFilters FilterType="includeAll" />
<ExternalLinkFilters FilterType="excludeAll" />
<LinkColumn LinkAttribute="System.Links.Description" />
<LinkColumn LinkAttribute="System.Links.Comment" />
<LinkColumn LinkAttribute="System.Links.LinkType" />
<LinkColumn RefName="System.AssignedTo" />
<LinkColumn RefName="System.State" />
Below is screenshot on querying for links and display for hierarchical link types.
For a tree query, the result list will have multiple levels displayed as trees.