This document was published by MS yesterday:
“This document provides guidance to help organizations understand and manage the security of the Microsoft® BranchCache™ feature introduced in Microsoft Windows Server® 2008 R2 and Microsoft Windows® 7. BranchCache is a wide area network (WAN) bandwidth optimization technology. To optimize WAN bandwidth, BranchCache copies content from your main office content servers and caches the content at branch office locations, allowing client computers at branch offices to access the content locally rather than over the WAN.“