MS has released a free tool that can help you search PSTs available in your network and export them to Exchange 2010 archive mailboxes of users. This product is originally developed by red gate and MS has acquired this and released as a free tool to encourage its customers to move from PST to exchange archives.
For more details and downloads, refer to below links.
Documentation: http://technet.microsoft.com/en-us/library/hh781036.aspx
Download : http://www.microsoft.com/downloads/details.aspx?FamilyID=f6006c4b-a6a9-4e83-81b3-e770d37f63ff
Video:
Hope this helps….