Announcement – http://blogs.technet.com/b/dpm/archive/2015/01/06/deduplication-of-dpm-storage-reduce-dpm-storage-consumption.aspx

The process is a little raw at the moment – http://technet.microsoft.com/en-us/library/dn891438.aspx

I imagine it will be one of things that is integrated natively into the next version of DPM – and becomes a bit easier to use when it is.