Actually, I believe we were running peer-to-peer, but I can't be sure as there is not much documentation about how it works. I know it runs over the normal Skype "channel" (but it doesn't use Skype audio). Most of my bandwidth seemed to be going to one site so perhaps vskype.com was serving us all. Something to look more into sometime.
vSkype doesn't have a whiteboard, but you can share your screen or any window. This feature worked very well.