Many Visual Studio users have a solution tree structure with multiple projects and solution folders that are organized as a deep hierarchy. To avoid visual pollution, users want only those projects expanded that are being actively developed (often with many of the project’s child nodes recursively collapsed). To accomplish this task, they have to manually collapse each node recursively – an onerous chore if one has a deeply nested solution tree. The Collapse Selection in Solution Explorer extension addresses this particular issue by enabling the user to recursively collapse multiple nodes with a single click.

Simply select the node or nodes you would like to recursively collapse and press the button on the Solution Explorer toolbar or use the keyboard shortcutCtl + Alt + Num(-) (Num(-) is the "-" key on the numeric keypad). Select the solution node to recursively collapse all nodes in the Solution Explorer.

Advantages over the "Collapse Project" functionality in "PowerCommand for Visual Studio 2010" extension:

You can multi-select nodes to collapse
You can collapse all types of collapsible nodes including VC++ Filter nodes, the white "ghost" folders you see in "Show All Files" mode for C#/VB projects, References node, files which have dependent files (e.g. Form1.cs <-> Form1.Designer.cs), virtual hierarchies (like Solution Folders), the "Miscellaneous Files" folder. If a node has a "+" sign to its left, this one will collapse it .

More information: http://blogs.msdn.com/visualstudio/archive/2010/05/13/announcing-collapse-selection-in-solution-explorer-extension.aspx