Work items can be view using different applications such as Visual Studio 2005 Team Explorer, Project 2003 and Excel 2003.   Via the Excel interface, you can select a field, such as State, across multiple work items and change the value (from Open to Resolved for example) at once.  See:  http://msdn2.microsoft.com/en-us/library/ms244375.aspx

 

i. Open Work Items in Excel and select the columns that you want to change.   The selected items below are in the Active state.

ii. 

iii.Change the field to Closed and press Ctrl+Enter.  Now all of the selected states become Closed.  

iv.