Paul MacKnight explained to us the new cmdlet export-mailbox that replaces exmerge tool.
Exporting Mailbox Content
Export-Mailbox is a task developed by the migration team to allow Administrators to export content from active mailboxes to a folder inside other active mailboxes. The initial idea for this task was to be a complete replacement for ExMerge. The implementation of some of this functionality was problematic and it required more time than initially planned. In this post I will describe what we are missing, which workarounds are available, and some of our future plans.
Read more at source: http://msexchangeteam.com/archive/2006/11/28/431669.aspx