I think this is more related to Windows clustering itself than to VMware. For the public network you I don't see any reason why this shouldn't run on shared uplinks. It's actually the private/heart beat network for which MS only supports dedicated NICs. Disregarding official MS support, I set up a couple of MSCS systems and never had any issues with heart-beats even if there wasn't a dedicated NIC available for it. What you'd usually do is to setup the private network as dedicated to heart-beat networking and the public network as both, public and heart-beat.
André
