From a pure technical point of view this will work, provided your network is configured appropriately (i.e. leveraging VLANs as well as separate subnets for Management, vMotion and iSCSI). However, I would be concerned about bandwidth and contention with such a configuration.
Btw. unless you already saw this, I'd recommend you take a look at http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf
André