This is an interesting concept. Branch Cache can be very good in low bandwidth remote offices. If this solutions works, it will be a tremendous boost to SharePoint. Some of the complains that you hear about SharePoint implementation is that it is slow in low bandwidth offices. Branch caching may not help in a Collaboration situation where too much of read write is going on but for everything else it is a great tool. It caches everything, for pages to images to office docs.
Here is a quick demo of it http://edge.technet.com/Media/Branch-Cache-in-Windows-7/
And for the whole shebang visit http://www.microsoft.com/windowsserver2008/en/us/branch-office.aspx