Voted as number three top most wanted features in DSpace 1.6. This JIRA issue will be used as a holding place for this feature, and potential code that could be adopted as a solution. See: http://wiki.dspace.org/index.php/Batch_Metadata_Editing_Feature
First version of this patch uploaded. Instructions at: http://wiki.dspace.org/index.php/Batch_Metadata_Editing_Prototype
This code will work with DSpace 1.5.2 (and possibly earlier 1.5.x versions).
Please try the code (on test systems) and comment.
Use cases included name and subject authority control, adding a new piece of metadata to all the items in a collection at once. One manager wanted to allow student assistants to bulk-edit metadata. Suggestion: export/import of a collection's metadata only, for batch editing. bulk metadata editing through a web UI