Microsoft has just announced they have released a tool that allow admins to automatically crawl users computers and import PST files into Exchange Online or Exchange 2010.
Download http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=28767
Thanks to the following blog for the info:
http://www.grouppolicy.biz/2012/01/out-now-official-pst-to-exchange-import-tool/