No, the bits always have to be copied over the network from the storage server, to the Hyper-V server, then written back to the Storage Server.
EMC and VMware are working on this in VMware’s vSphere 4.1 release, but it will only work with EMC storage arrays. I’m sure others will latch on to these APIs in the future but for the next year or two at least there won’t be a way to fix this other than to increase the network capacity. You’ll also need to make sure that you aren’t maxing out the performance of the disks that are on the storage server. That will be the performance pain point before the network is.