After creating a striped array in my MacBook Pro, my network copy speeds have roughly doubled when copying to the fast (and ridiculous) disk setup in my Mac Pro. I used to see copy speeds of 30-35MB/s at most; now, it is not uncommon to get sustained copy speeds of 65MB/s or more. I've even seen it burst up to 90MB/s.
Obviously, this only happens when I'm copying large files, like virtual machines. For normal file copies over the network, I don't see much of a difference.