You can also add elements to the Metadata element that define workflow task types as bulk editable. Bulk editable tasks are workflow tasks that can be edited as a group. For example, a user might want to mark all tasks of a certain type as 'complete' for a given workflow template.
In addition, by using an InfoPath form as the workflow task edit form, you can include logic in the InfoPath form to switch form views depending on whether the user is editing an individual task or bulk editing tasks.
For more information, refer to the following blog entry:
http://blogs.msdn.com/andrew_may/archive/2007/01/12/SharePointDefineBulkEditTasks.aspx This information will be included in the next update of the Office SharePoint Server SDK.